OK Yesterday morning I went out to start the car. It would crank and crank and crank and crank and never start. I know my battery is good since I spent like 5 minutes or more cranking :-). Incidentally it was about 16F out.

If I opened the throttle partway (1/3-1/2) the engine would turn itself over once... I could tell it fired, but it just wouldn't keep going. It was doing it over and over and over again (as I was still cranking the starter), eventually it got to the point where it would fire twice, then three times, then FINALLY it started. It ran REALLY rough, choppy, I had to keep the throttle open partway (but if I opened it farther it ran worse) for the first 10-15 seconds, before it started smoothing out. After 30 seconds I let my foot off the gas and it idled OK, getting smoother as it warmed up.

I've done a lot of ignition stuff to it, and I just did a compression test a couple weeks ago (compression was good). The guy at autozone suggested the carb trick for testing fuel: dump an ounce of gas down the throttle body, then try to start. If it starts fine, there must be a fuel delivery problem. If it still won't start, it's probably NOT a fuel delivery problem.

So I tried that this morning. Sure enough, car fired up after about 4 seconds of cranking (still ran choppy for the first few seconds after that). However, the temperature was a little warmer, maybe 20-25F. So, I bought a fuel pressure tester. Hooked it up, pressure is dead on 11 psi (TBI range is 9-13). And I mean the needle is solid as a rock. Rev the engine, put a load on it (put it in gear (automatic), hold with brakes, rev up to the stall speed) it stayed dead even 11 psi. Nothing I did would make it budge.

One interesting note, when I turn the key to ON but don't start the engine, the fuel pump runs, pumps it up to almost 11 (maybe 10.5 psi) and then cuts off. The pressure drops back to 0 in about 10 seconds... Is that a normal time? Or should the system hold pressure longer than that? Let me emphasize, this is with the key still in ON. I know it depressurizes after turning the key to OFF.

I know I don't have leaking fuel injectors because I can see them. The spray pattern LOOKS ok to my eye but of course I can't tell by looking how much volume they're spraying or if there is a difference between the two injectors (well, there's no obvious difference, but there could be like 25% or something which wouldn't be visible to the naked eye).

So do you guys think it's a fuel problem? What else could cause this kind of cold start issue? I have changed the computer, all sensors except VSS, IAT(MAT), MAP (IAT and MAP tested good with a voltmeter). The computer isn't throwing any codes (not even after cranking for 5 minutes without starting).

Other info: I sometimes get audible knock in high-load situations. Timing is set to 2 degrees advanced (stock is 0 degrees advanced). Actually I may have reset it to 0 degrees. Knock is unaffected by 93 vs 87 octane gas. Engine runs a little bit rough at idle, and it always has, even immediately after tuning it up. The plugs are dark and shiny, as though I were running rich. I get fairly poor gas mileage (20 mpg highway, TBI is capable of almost 30), but O2 sensor is a 1.5 years old or so. The ignition is tuned up (plugs (GM recommended) and wires (MSD 8.5 superconductors) are like 2 or 3 months old, cap and rotor(Accel) are 1.5 years old, air filter is a K&N, fuel filter is 1.5 years old, like I said almost all sensors are new, fluids are new (coolant, tranny, oil, power steering) vacuum hoses are almost all new, no vacuum leaks that I can tell, intake manifold gaskets are new, PCV valve is new.

Help me! This car is killing me!

 

EJ,

Lots of good information - that should make it easier to diagnose. You have apparently proven that you aren't getting the correct fuel to start by your test.

I would suspect the CTS and/or IAT are sending the wrong data to the ECM. In order for the ECM to use the cold start fuel tables, the CTS must be below 104°F and must be within about 10° of the IAT sensor reading. If the IAT circuit is open, it will show about a -40° reading. If it is shorted, it will show about a 285°F reading. In either case, the ECM will be confused, and may not be using the cold fuel enrichment tables.

Your fuel pressure is dropping off a little fast, but at least the pressure is correct when the pump is running. The pump should only run for about two seconds when the ignition is first turned on. The pump will operate again when the distibutor is turning, the ECM gets a "cranking" signal from the starter solenoid, or the oil pressure switch closes at about 7 PSIG. This is all normal, and shouldn't be a problem.

The injectors will not pulse unless the distributor is turning and the MAP sensor is reporting a lower mainfold pressure (it must see some vacuum). If the MAP is working correctly, the injectors shoudl deliver some fuel. If the IAT and CTS are correct, the fuel flow should be greater than at a warm start.

Check the PCV hoses, the EGR valve, and the TPS voltage. An open-circuit at the TPS can cause the ECM to stop delivering fuel. You might want to check the hose to the MAP sensor as well. To temporarily force a higher vacuum as a diagnostic tool, you can plug the PCV hose until you are running. You might also want to make sure the IAC passages are clean.

Waiting for results.

------------------
Later,
Vader
------------------
"No matter how hard you try you can't stop us now"
Adobe Acrobat Reader 4.0

[This message has been edited by Vader (edited November 23, 2000).]

 

Ok, this sounds really familiar since my car spent two weeks in the shop with the same syptoms. Mine never threw a single code either. One thing to try would be to disassemble and clean your IAC valve, or you can replace it if you don't wanna mess with it. I got my car back yesterday and it was running great. The problem turned out to be the MAP sensor. Cost a little over $50 for a new one. That's about the only thing I can suggest. One more thing, is your car running rich??

 

I have exactly the same problem! 28 degrees or below requires partial throttle to start.
No problems spring, summer and fall. My car is a 1991 RS 305 TBI w/ 35,000 original miles. Did the same thing last winter (1st winter I owned the car) w/ 27,000 miles. New parts: CTS sensor, distributor cap and rotor, sparkplugs, coil, plug wires, O2 sensor, fuel filter, thermostat. Car is bone stock. Only does it after sitting all night when temps are as listed above. Let me know if you figure it out and I will do the same. Hopefully, this thread will stay active and we can figure out whats going on. i have not
looked at IAC or TPS since others have done this and still experience the problem.
btw, ecm does not set any trouble/error codes and seems to be getting plenty of fuel but i have not observed any other tbi camaros to compare.
Matt

vader and soulbounder:
thanks so much for the replies i didnt see them when i posted a reply. Ill check my MAP sensor today and plug the PCV tomorrow morning b4 I try to start car, although the temps are supposed to be higher starting tomorrow until next tuesday. soulbounder, car run rich and gets poor gas mileage.
having said all the above, car runs smooth ie, no hesitation, surging, etc. no other symptoms or problems.
later

[This message has been edited by Matt_Ky (edited November 23, 2000).]

 

OK Vader let me see if I can answer all your questions.

CTS is new. Mostly because it was $8 so why not, but the new one is reporting the correct values (or at least, it always has when I tested it, I didn't check it yesterday). The IAT has also always reported the correct values so I have never changed it. The CTS, IAT, and TPS all use the same ground and I was occasionally getting a code for one of the three (a few months ago) but I found out that the contacts for one of them (forget which) in the connecter were bent back and making poor contact on the ground side. I fixed that and haven't gotten a code since. The TPS is new, the old one reported the correct values except that there was a tiny flutter in the voltage when you made small throttle adjustments. The new one does not have that flutter. TPS doesn't get adjusted, this is a 92 so the computer self-adjusts.

Yesterday when I was having so much trouble starting, the injectors WERE firing. I removed the air cleaner and watched. Now, I have no idea if it was using the cold start enrichment or not (can't tell that from looking) but they were not shut off or anything.

I'll try cleaning the IAC passages again, I cleaned them last year a few times trying to fix my bog/cold stall problem (on start, the engine catches, then bogs. Bogs worse in colder weather, to the point where it'll stall if it's cold enough). The IAC itself is new (a little over a year old). I would be very suprised if it has any effect, it never did before.

The hose to the MAP and the hose to the PCV are both new (as is the PCV valve). Thinking I had a vacuum leak, I replaced all my vacuum hoses this past spring :-). Well, all but one, but it was on the same vacuum circuit as the brake booster, and that circuit holds vacuum for over 5 minutes after the engine stops, so I don't think there are any leaks on that part. I used a vacuum pump and a voltmeter to check the MAP sensor, it smoothly changed voltage as I applied more vacuum so I think it's good.

Soulbounder, as I said above, the car gets less gas mileage that I think it ought to, and the plugs are dark (brown/black) and shiny, which would both indicate a rich condition. Paradoxically, I also get engine knock sometimes, which can be indicative of a lean condition (or screwed up timing).

Speaking of timing, how would I know if the timing chain jumped a tooth? The engine has 150,000 miles on it, so a timing chain issue is a possibility. Unlikely to be the problem here I think since Matt has a very very similar problem and his car had 27,000 miles on it when we discussed it last year :-), but I'm still curious what it would be like. It may be my car has multiple problems.

Thanks!

Oh the one thing I think might help would be to hook up a scanner to the computer before starting first thing in the morning. That way I could see what the computer was receiving from all its sensors, and rule them out for good. Unfortunately I don't have $300 to buy a scanner :-(, and I don't know anyone who has one I can borrow.

If you're curious, here were the compression test results:
8-202 7-205
6-211 5-209
4-196 3-211
2-202 1-204
As you can see, nothing really glaringly wrong. 4 is a bit low but not enough to make me think there's anything wrong, overall average was 205, that's a 4% deviation.

 

OK Since there were no forthcoming suggestions, here's what I'm going to try. First thing tomorrow, I'll disconnect the IAT and CTS. That way they will both read -40. If nothing else, the computer should run in "limp home" mode, I.E. rich as all hell. Either way, it should be as rich as the computer can possibly make it. If it still has starting problems, it must be a mechanical fuel issue (fuel injectors sticking when cold?). If it does NOT have starting problems, I can assume that they are the fault of a confused computer. Comments?

 

I'm talking to myself here! C'mon, doesn't anyone have any ideas?

Well, bad news this morning. It was down around 20 again, disconnected IAT and CTS and checked them with an ohmmeter. 11,000 ohms or so, which (according to Chilton's) means about low 20's. So they seem accurate.

I tried to start the car without them plugged in (so it should be in "rich as hell" mode). Crank and crank and crank, no start. I tried dumping gas down the throttle bores again, this time it didn't help! Reconnected the sensors, same. More gas, same. Finally got it to start after enough cranking, but now I don't think it is a fuel delivery issue any more. I think it was cooincidental that it started yesterday after adding gas, I think it was the temperature (25, maybe even higher because the car was in the sun) that made it start easier.

Well, on one hand, that sucks because I'm back to having no clue what is wrong with it. On the other hand, I think I've pretty well verified that the fuel system is NOT it.

So, what if it were a timing issue? What symptoms should I be seeing if I have a slipped balancer (so I'm setting the timing way off) or a timing chain that jumped a tooth?

Oh and I could definitely hear the uneven note in my exhaust today (after I got the car started and idling). The exhaust is a nice roar (idling at 1500, because it's in warmup mode), punctuated by kind of a WHUM every so often (not regular).

I'm tempted to give soulbounder's suggestion a shot (MAP sensor) except that every time I've heard "Oh I had that exact problem and it turned out to be XXX sensor", so I replaced XXX sensor, it didn't help. I'm not sure I want to throw another $50 part at it... although of course I just spent $65 on a fuel pressure gauge that merely showed me how well my fuel system works.

 

Sorry man, I don't know what to tell you now. When my car was in the shop it was hooked up to a scanner and it pointed directly to the MAP sensor but I don't think that was the problem now. I get my car running great on Wednesday, park it in the garage, and when I tried to start it up yesterday, gave me the same old trouble. I don't know what to do anymore. I'm going to try a different mechanic and see if he can figure out what the hell is going on. If I get any leads I'll post them here. l8r and good luck.

 

Ok, I may be on to something here. Today I changed my spark plugs and boy did they need to be changed. After I was done, I had the air cleaner lid off and I started the car up. It cranked and was running really well. I turned it off and tried to start it again and well, it didn't want to. Some of my friends were with me so I held the pedal down and started the car but it was running rough. With the lid off we all gathered round and took a look at what was happening with the injectors and tb's. There was a very loud hissing sound, I do mean very loud too! While at idle (I could be wrong about this) the injectors are supposed to sorta sputter out fuel at a constant rate, not a constant spray. Well, turns out that at idle my injectors were not sputtering the fuel right and they were putting out too much fuel almost like a spray (like when you rev the engine). The fuel was actually puddling up on the blades of the throttle bodies. Well, this excess of fuel flooded it causing it to die out. After letting it sit for a while I started it back up and it ran fine after it warmed up. When I started the car up again I went back to take a look at what was going on under the air cleaner lid and there was no longer a loud hiss and my injectors were sputtering like they are supposed to. I don't know what the cause of the trouble was but it seems to have disappeared for now. I have a new IAC valve and MAP sensor on my car. Does anyone know what could be causing the injectors to spray like that at idle? I'm gonna try to clean the injectors and hopefully that fixes the problem. Good luck everyone with similar trouble! l8r

 

EggPlant,
Hang in there man! I'm going to check sensors (again) and hose connections tomorrow. I'll post the results. I did install a new fuel filter today today when I changed the oil. Temperatures are predicted to be in the mid-30's at night until next Wednesday so Im not sure I will see the cold no-start condition until then. I have noticed the same thing you did about sitting in the sun. It seems to eliminate the problem. Lastly, Ive noticed its time related it addition to temp.
If it sits 4-5 hours no problem. Mine occurs if 7-8 hours or more, ie, all night.
Later
Matt

 

As far as Soulbounder's problem goes with gas puddling up on the butterflies, I'd almost bet my bottom dollar that the O-rings around the injectors are worn out. Mine was doing the exact same thing. I almost bought new injectors, but was told they hardly ever go bad. I tore my throttle body apart, and the O-rings were trashed. I got a rebuild kit from Napa for about $30(the cheapest price I found), and it included the O-rings, new filter screens, pressure regulator diaphagm, and all the gaskets you need to reassemble the throttle body. A couple of tips on replacing the O-rings. Lubricate them with ATF, and tighten the metering plate screws down evenly a little bit at a time. This will prevent the O-rings from binding or seating ****eyed. My throttle body hasn't given me a lick of trouble since I replaced those O-rings. Unfortunately, I didn't figure this out until I'd spent a ton of money on a new MAP sensor, O2 sensor, and even a new fuel pump! And we all know how much fun it is to replace the fuel pump!

 

Soulbounder, the only thing I can think of for why it was spraying so much fuel is that it was in warmup mode and trying to idle the engine at high speed (1500 rpm or so). Thus the computer was dumping extra fuel in there. I don't think fuel condensing on the throttle blades is really a problem. If you really had puddles (I.E. it was spraying as fast or faster than the fuel was leaking past the throttle blades) then that's probably not right, but at idle drops of fuel are going to form on the blades... when you spray mist at a (nearly) horizontal surface, it wants to condense.

When you say you turned it off and tried to start it again and it didn't want to, do you mean you tried IMMEDIATELY to start it again? Or you tried hours or days later?

As far as the O-rings go, first you can get a kit from Autozone that has everything in the kit Pat mentioned EXCEPT the FPR diaphram, and it's 15.95 I think. They also have one with the diaphram, it's like $30 (probably the exact same kit :-)). Secondly, been there done that. Nothing wrong with my old O-rings when I took them out, I put the new ones in anyway since I had it apart. But it's worth considering since for $16 a rebuild of your TBI unit is probably worth it, even if it doesn't fix anything in particular. You can do the AFPR mod at the same time :-).

Matt, you're right about it being time as well as temp. For example, I started my car the other day, had trouble. Got it started, ran for less than 5 minutes (definitely didn't finish warming up) and shut it off. Two hours later, I went to start it (still just as cold out) and it started on the first crank, no bog, smooth as anything.

I'm starting to wonder if it might be a more serious problem... What if there's a valve that's sticking when cold? After warming up, the heads would be warm (so the metal expands slightly) and everything would be well-oiled, so the valve doesn't stick. But after sitting all night, the oil has completely drained back into the oil pan plus the heads are cold, so the valve sticks. I have no idea how plausible that is but I'm kind of running out of ideas. Unfortunately the only way to check this sort of thing is remove the valve covers and watch/measure rocker arm travel (just the sort of thing you want to do in below-30-degree weather).

 

EggplantJeff,
TPS checked out ok. MAP readings were all over the place. I couldnt get the DVM to stabilize for some reason (I gotta get a scan tool). Yes, it is definitely time related. 7am the cold no-start occurs, lunch time (~ 4-5 hours later) no problem even though the temperature is still below 28 or another scenario, if my son takes the car to school he does not have a problem after the car sits from 7:30 to 2:30. However, when the car sits from 9-10 pm to 7am BAM it happens.
Im still leaning towards fuel delivery or possibly the ECM. If I recall correctly, this same discussion last winter was mostly early 90's camaros, all TBI. Do you recall? Just wondering if anybody with a TBI car had this
problem and then switched to carb, TPI, etc
and the problem disappeared.
Later!

 

i have the same problem and the only way i could get my car [89rs,tbi] to start in the mornings was to plug in the block heater to keep it warm. if it got cold overnight..it would take a solid 5 mintues of idiling before i could drive it away. always runs fine in warm weather though....

 

Matt, yeah I remember it from last year. Well, MAP is a possibility if yours was all over the place. What was the temperature like (and engine temp) when you were checking? I checked mine but I think it was probably warmer than 30 when I checked it. Maybe the MAP becomes less accurate at cold temps when it gets old.

I am curious, Matt, Soulbounder, do you guys have the stock air cleaner, or an open element? I've got an open element. I'm wondering if the extra air flow might be confusing the computer. I'm thinking of covering all but 3 square inches of my open element and seeing if that helps.

 

Stock air induction
MAP/TPS checked at ~ 48 degrees

32 deg this morning - no cold start problems

 

Here's something new for today. BTW, my engine still has the stock air cleaner, in fact, everything is stock. Well, today after school lets out, I get in my car and it starts without any trouble. While driving down the road (just taking off giving it part throttle) the car starts to jerk. I let off and procede to accelerate again. Same thing happens only not as bad. It did not jerk back and forth like that at WOT, only partial throttle. I don't like to take off fast and some people even say I drive too slow. I think I will invest in that kit for the TB. How much time did it take to rebuild (Please consider the fact that I have never done this but am highly mechanically inclined without a whole lot of experience.) I guess I just need to keep looking for the problem. Thanks for the help EJ. l8r

 

Soulbounder, it took me about a day (I also had no experience), but I did the ultimate TBI stuff at the same time (ported the TBI unit, made my FPR adjustable). If you were just going to do the rebuild, probably half a day. Do it on a saturday so just in case it takes longer you have sunday to finish it on.

 

Hey guys,
I am the one whos tryin to help soulbounder with his car. Its a very disturbing situation. So, should a TB rebuild take care of this? I find it strange that it runs great sometimes, then wanting to kill other times. I thought it was his fuel pump at first. I know that when the injectors leak, it can cause flooding. Just my .02

 

Injectors are easy to check. Remove the air cleaner, turn key to ON (don't start engine). The fuel pump will put pressure on the lines, look at the injectors. If any fuel drips out, the injectors leak (well, you can tell whether one or both leak). If no fuel drips out, the injectors don't leak.

I have no idea if the TB rebuild will help him. I would think if the O-rings were bad, you'd see leaking fuel if you do the test I just mentioned. But mine were not bad so I really don't know. It's worth a shot (since it's inexpensive and gives you an excuse to do the ultimate TBI stuff), but it is definitely not the cure for the type of problem Matt and I are having.

 

Ok!!! I think my problem may be solved. I brought my car to a different mechanic and he hooked it up to a scanner but it didn't show anything wrong. He took it for a drive and noticed that the temperature never got about like 120. Immediately he thought there had to be something wrong with the thermostat. Well he changed it and now it's like a world of difference. My car runs smoothly and has no trouble starting. I got it back today after bringing it to the shop yesterday. I'm just curious, EJ, Mattt, did you try changing your thermostat?

 

soulbounder/eggplant,
yes, i changed to a 180 thermostat, installed a dash mounted manual fan switch, etc right before the summer months this year. i did this for other reasons and because the original owner was a mid-40's couple that changed the oil regularly and that was about it, so i changed all fluids, replaced a few ignition components, fan belt, alternator, battery, new brakes, tires, etc.
anyways, the temp has been in the low 30's here in louisville in the am, so i have not been able to further diagnose the problem.
what is the ambient temp when you did not experience the cold start problem?
i seriously doubt the thermostat is the problem, but hey, im open to any suggestions at this point have you wired your fan to run all the time? just curious why your engine temp doesnt get above 120.
later
matt

 

I don't have a fan rigged up to run all the time. My engine is %100 stock. My engine would actually get hotter than 120 but the thermostat was malfunctioning and sending the wrong data to the computer. This in turn kinda wacked out other sensors but never threw a single code. I think it was replaced with a stock 195 degree stat and it's still running great.

 

Oh BTW, down here in south Louisiana it only gets to maybe 40 if that. The problem I was having didn't seem to be affected by temperature though.

 

I never thought about the temp. Looks like that thermostat was the problem. Now we can sleep at night. Congrats soulbounder!!

------------------

 

Glad your problem is fixed, soulbounder. However I want to clear up one point :-). The thermostat doesn't send any data to the computer. The thermostat is basically a plug in the intake, just below the water neck (where the upper radiator hose attaches to the engine). It has a calibrated spring sort of thing in it that expands as it heats up, opening a passage through the plug, and allowing coolant to flow through the radiator. If it were stuck open, the car would run too cool (but only in very cool weather. In hotter weather or in traffic our cars need the fans on in order not to overheat).

There are two coolant temperature sensors, one drives the gauge you see on the dash, the other tells the computer what the temperature of the coolant is. If that one were screwed up, the computer would be confused and cause wacky problems. This is probably what your new mechanic was talking about. The gauge should still be reporting the correct temperature, but when he looks at (via a scanner) what the computer thinks the temperature is, he would see a large discrepency.

 

Oh and just for info, I do have a new 180* thermostat and manual fan switch (temperature fan switch in the head is not connected, the connector fell on the manifold at some point and is hopelessly melted). The engine doesn't like running very hot, if it gets much above 180 (200-220 say) it really starts bogging when I jab the gas and let off right away... just like first thing in the morning when it bogs after starting.

But my engine will stay exactly at 180 when I have the fan on, thanks to my Stewart Stage 1 water pump. Man was that a well-spent $80. In traffic, on the hottest day, it will maybe get to 190.

So Matt, it looks like you and I are the only two who have the problem we're discussing at the moment. I think there was at least one other guy last year, camaro68 or something, but I haven't seen him in a while.

I'd have to say, it must be something that is damaged by AGE not by miles (since I have to many miles and you have so few, but our cars are the same age). The sensors are all good things to check, but I think we've checked them all. What else would there be? Hoses, exhaust... Hey how is your exhaust system? Is it stock? What condition (any holes)? Mine has at least two holes, one of which may be patched (wrapped a wraparound clamp over it). I don't see how that could cause a problem but... Both holes are downstream of the y-pipe though so I doubt they would be contributing to uneven running.

How does your car run when it gets warmed up? Does it exhibit the same bogging that mine does? Just as the car bogs in cool weather (and stalls in cold), when the engine is hot it will bog if you tap the gas pedal (such as moving up a few carlengths in traffic).

My engine was knocking again today, really frusterates me. The knock is completely independant of temperature (engine and air), and octane, and timing. Seems to me that the only thing left that could cause knock is mixture, but that seems more or less correct, I think...

I wish one of the really knowledgable guys would offer some suggestions... I've stumped everyone I've told this problem to.

 

Yes EJ, sorry about that, you are totally right about the thermostat thing. I got confused on what the mechanic said compared to what my parents tried to say. From what the mechanic told me directly, he said that my car was having trouble with open and closed loop. Something about it would stay in open loop all the time. I'm not very experienced with cars but I am actually making an effort to learn. Good luck with your problem

 

Eggplant,
Im running factory exhaust. As far as I know no holes/leaks. Car runs great after warming up regardless of ambient temp. No bogging or stalling. Occassionally it will surge slightly but other than that no problems. the temp is supposed to be in the high 20's tonight or tomorrow night so i may get a chance to try a few things. also, im going to contact a few chevy dealers and see if they
have seen this problem before, maybe you could do the same and we can compare notes.
lastly im going to see if the part#'s for the TPS and MAP sensors for a 1991 vin E are the same for a 1992 305 tbi. btw, there is a TSB on the TPS for 1991 camaros regarding intermittent problems but i havent researched it yet.
later
matt

 

Ok, this is the first time I've seen this topic although its pretty old and after reading what seemed like forever in posts I'd like to throw my $.02 into the melee...

Some background info... '91, L03, 121K miles, completely stock (not even Ultimate TBI YET), new fuel pump, new O2 & TPS sensors, new cat, new plugs (Rapidfires) wires (Taylor 8mm Spiro's) rotor and cap (both Wells with brass connectors) but am experiencing a failing pickup coil, timing should be at 1* advanced but after going to the mechanic and dealer I don't know and I've heard a bit of pinging lately so I have to check that out again. I don't know if my other sensors are working fine or not but I have been getting these codes after doing 70 on the highway: 23, 32 and 34 but I have a feeling that its the EGR valve not working right.

I had a problem that started way back in July where the car would lope heavily in the mornings when it was cold and sputter under load and off starts, ie: traffic lights, traffic, etc. I finally had it diagnosed and had the fuel pump replaced (although it was showing perfect fuel pressure - and EJ where the hell do you do get a kit to test FP on a TBI??). All during this time the car would start up fine in the mornings regardless of the ambient temperature. Although when after it was fully warmed up and had been running for a while then shut off and let to cool off to about 150* or so, trying to start it would be a PITA, it would immediately stall each time. I had to get my foot on the gas eventually and keep pumping the pedal to keep it running. After about 5 seconds of that it would finally even out (this was before the pump replacement).

Now that I've gotten the pump replaced, I've noticed that its harder to start in the mornings (usually around 25*-40* ambient temp). My problem isn't as bad as some of your's though, all I have to do is let it turn over and when it catches, just pump the gas one time before it starts right up - no idling problem whatsoever. Maybe its a weak fuel pump relay - I've read in some other posts that extended crankings are usually a sign of that.

Or one other very simple thing that nobody's mentioned yet. When the weather turns colder, water in the tank and fuel lines creates more of a problem. I haven't put any DryGas or gas line antifreeze in yet to test this out but it might be worth a shot!! That would be one really cheap way to fix a problem and I wouldn't be surprised with all the stupid little anomalies these cars throw at us.

Sorry it was so long but its better than a bunch of little posts.

P.S. soulbounder, when I take my air filter cover off my injectors are always making a loud hissing sound, I just thought thats the normal sound they make. They do sputter at idle and spray evenly at open throttle though.

------------------
'91 Firebird
305/TBI(L03)/700R4/T-tops
Mods: Catco high flow cat - B&M Shift kit - TA tail light conversion - K&N - White faced guages on the way
Stereo: Pioneer DEH-P8200R - Pioneer 6x9's - Kenwood 8" Tube

'87 Firebird
2.8L/MPFI/700R4/220K
Twas a good car until the accident.
Firebird parts

[This message has been edited by pianiy (edited December 03, 2000).]

 

Pianiy,

Matt and I have no problem starting when the engine is warm. In fact, if the engine is even a little warm (sat for less than 2 hours) it starts like a champ, I mean, FIRST crank and vroom there it goes. So I doubt our problem is fuel pump related (or at least not the exact same as your problem).

You can get a fuel pressure kit from Autozone, it's actually called a GM TBI fuel pressure kit. It comes with a T-connector you put inline in the supply line (not the return line) and a pressure gauge (it is a diagnostic tool, not a permenant guage, I would not leave the T-connector inline permenantly). It's made by Actron, I think Summit (or Jegs, forget which) carries it as well if you don't have an autozone around you. It's about $60.

DryGas is worth a shot, I haven't done it ever.

In my "What causes knock" thread, someone suggested that excessive wear in the cylinder bores would cause knock... it seems conceivable that it would cause uneven idling and hard starting too, especially if it's only bad in a few cylinders. Hard to believe that this could be Matt's problem though since he's got a whopping 30K miles (unless someone ran his engine with no oil).

Oh I meant to tell you about the other day. Sunday I fired my car up in the evening (but it was COLD out (low 20's, high teens), it was after the sun had gone down). It had been sitting for about 20 hours I think. Hard to start, then when it did, I got a big cloud of blue smoke (oil)! This car has NEVER smoked except ONE (1) day last year (similar situation, had sat for about 2 days, VERY cold out) when it did the exact same thing. What the heck?

 

Just from experience here. I would get rid of anything that is made by "wells". That is an autozone/advanced auto brand and i personally have had nothing but problems with that low quality crap.
Get a delco or atleast another decent brand.
Mainly had problems with the cap. The would work fine when you get them but they degrade in quality very quickly and stop conducting electricity worth a damm.
Just rambling on here. Doesn't really help the topic too much but maybe it did?
I used to have a 91RS L03 about a couple weeks ago. I had the same problem... i really wish i knew what the problem was myself.

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1987 IROC-Z L98 350 SuperRam, Edelbrock Performer 6085 Aluminum Heads, LPE RollerCam 219/219, Crane Gold Race 1.6RR, TF 1 pc Chrome Moly Pushrods, Underdrive Pulleys, Edelbrock TPI High Flow Base Manifold, Accel 58mm TB, ADS 24#, Crane AFPR, K&N, Edelbrock TES Headers, Catco Hi Flow Cat, 3" Borla Cat-Back, Accel Cap & Rotor, MSD 8.5mm, MSD 6AL Ignition, MSD Blaster 2 Ignition Coil, Hayes Clutch, 1LE Aluminum DS, 94' Z28 Disk Rear, Wilwood Adjustable Proportioning Valve, Torsen Series 3 Posi Carrier, Precision 3.73 Gears, Southside Machine Sub-Frame Connectors, Hotchkis Lower Control Arms, KYB Shocks/Struts, Suspension Techniques Lowering Springs, Polyurethan Bushings all over the place, Moog Upper/Lower Ball joints and Tie Rods ends/Idler Arm,

 

Damn long thread guys! My firebird L03 has 120K on it with no cold start problems except that if you touch the gas after the warm-up process it hesitates for a few seconds. NOW THAT FU(ING KNOCK IS SOMETHING I WOULD LOVE TO KNOW ABOUT!!!! Every time my car gets hot, around 200+ degrees I have an engine rattle with an idle misfire. It sounds like pinging. Oh and have I changed anything, you bet. Try O2 sensor, plugs, wires, cap, rotor, ignition coil, pickup coil, timing chain, and all sensors check out fine on a scan tool. Not only that, I checked valve lash, all hoses, replaced EGR valve after getting the code 32 all LO3's get, done a compression test (all good), and the damn engine misses at idle and knocks. GUESS WHAT, I KNOW WHAT THE PROBLEM IS!! 305's are notorious for valve guide wear. When the guides wear then oil contamination get's into the cylinders and causes pre-ignition. Oh but wait! I have a milky substance in my air cleaner housing. Could that be blowby from worn compression rings? YUP! Even after a good compression test? That's because a compression test can't simulate the pressure of the combustion process at off idle RPM. Hope this helps.

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84 Camaro ZZ4 with HOT cam. 1.88 60' (12.98 @ 105MPH E.T.)
Other Mods: You name it and I have probably changed it.

91 Firebird 5.0L TBI

ASE Certified Auto Tech
LIVE AND DIE BY THE ALMIGHTY BOWTIE!

 

EJ,

Another thing you might want to try is to slightly adjust the minimum air position of the throttle to a larger opening. Adjust only enough so that the IAC can still compensate and control the target idle speed.

Knowing the vacuum reading at idle might be helpful. We already know the fuel pressure is steady at 11 PSIG.

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Later,
Vader
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"No matter how hard you try you can't stop us now"
Adobe Acrobat Reader 4.0

 

Latest data:
1. 31 degrees F snow falling - cold no start (first time it failed to start when temps are above 30). only difference snow/moisture
2. 18 degrees dry - no cold start problem (first time it ever started at this low of temp w/o partial throttle) go figure!
Damned if i know, taking off friday to try and figure this out, arggghhhhhhh!
Later,
Matt

 

Sounds like this problem is mainly with 90 and newer L03's. I have an 89 L03 with 155,000k, and I've never had a single problem with it starting in cold weather. Even in subzero temps, it starts right up without even touching the gas pedal. I'm interested to see what you guys end up finding out on it! Hey EJ, what did you do with your IAT sensor when you went with an open element? I wonder if that might be causing some problems?



[This message has been edited by Pat Hall (edited December 07, 2000).]

 

Vader, I forget the exact number for vacuum at idle but it was high. 21 inches? I'll check again sometime soon (I'm moving into my new house (yay!) this weekend so I won't be working on the car at all :-)). I'll try opening the idle stop a bit, but I've adjusted it a few times with no change (in different temperature weather).

Oh yeah! I just remembered. A while back I was working on this and kind of forgot about it... At idle I have a little bit of a "lazy needle" on the vacuum gauge. It wanders back and forth about 1/2-1 inch (say 20-21 or 20.5-21.5, something like that). Not fast like with a miss or something, nice and gently. I lowered the fuel pressure and replaced the ECM and it was reduced (it used to be 2 inches or so) so I kind of forgot about it, but I'll bet anything that it wasn't "fixed" by either thing, it probably just became less evident.

When I went to the open element, I drilled a hole in the filter base and mounted the IAT in it (basically just like stock). Months later I removed it, covered the hole, and mounted it to the firewall ("IAT relocation mod"). Absolutely no difference whatsoever :-), I wouldn't say the mod is worth much. Actually it is worth one thing, when you remove the air cleaner you no longer have to disconnect the sensor.

 

Back to top, any ideas Vader?