Hey guys, i'm pretty sure im starting to go crazy. I've been troubleshooting my car for a while now. It's a 1987 IROC, 305 TPI 700R4, with the A/C and Emissions removed. I made another post about this, but didn't wanna dig up an old thread, so here goes: When i bought the car about a year ago, it ran well for about 3 months, then it started to develop a severe misfire. That ended up being the cyl no. 3 spark plug wire, it was sitting on the manifold and melted. When i fixed that it ran ok again, but never the same as it was. About a few weeks after that, she started to bog down when you accelerated, until about 3500 rpm, then it would clear up. This made the car pretty much no fun to drive. The car also developed a starting problem, if the motor had been running, the car would fire right up, but if she sat for more than about an hour, i had to crank it for 5-7 seconds, which was a giant p.i.t.a.....I decided to park her and get a junk car to drive, as my IROC was my daily driver. I was low on $$, so she just sat around for a while, i'd occasionally go out and fire her up, but could barely even drive car due to the hesitation. She was also idling erratically, moving around from 650 to 800 slowly. When she warmed up it would get a little better, but not much. Now a month or two since then has passed and im ready to work on her again, but she just turns over and over, and won't fire up. Bummer. I can crank her all day, but no luck, although she does sound like shes trying, every two cranks or so, you can hear it "catch" and almost fire up, but nope. I'm no noob to 3rd gens, or f-bodies in general, but im stumped. She's getting spark, im pretty sure shes getting fuel, as after i turn it over, the plugs are wet. I've got fuel pressure, not sure if its spot on, but if i push in the schrader valve on the fuel rail, it squirts about half a foot in the air....gotta pick up a gauge to check that. The cap+rotor were replaced a couple months ago with Accel parts, and i also replaced the main coil, plugs, and wires. When i touch the cyl 1 plug to the strut tower bolts and crank it, it makes a big yellow spark. The car wasn't throwing any unusual codes either, only 54, which i thought was cause i took the emissions off. I've unplugged the MAF and cranked, no difference. I've unplugged the ECM and cranked, no difference. And now i'm here, i don't want to throw money and parts at her wastefully, so now i need some experienced help. Only odd thing i noticed so far was when i pulled out the computer, it had already been replaced by the previous owner with a remanned unit, but i'd think she'd fire even with a faulty ECM. Where should i go from here, what should i test, and how? I have access to a multimeter, just not sure how to go about testing the different sensors and what their values should be at. I was mentally ruling out the ECM and MAF, cause from what ive read the motor will still fire, even with malfunctioning ones. I was thinking the other day that maybe the code 54 might have something to do with oil pressure, cause sometimes my oil pressure gauge flutters, and maybe that low oil pressure switch was preventing the car from starting, i have no idea. Im hoping the problem isn't internal, but the car does have 140k miles on her. She never made any odd noises, so i kinda ruled that out, but again, i could be totally wrong. Could any of this have anything to do with my cold start injector system? Well, anyone who feels like throwing in their ideas, id appreciate anyones help and direction. Is anyone in the Allentown, PA area? maybe i could get a hand. Well, thanks for taking the time to read this guys, i appreciate it.

 

sorry for the novel-esque post btw. oh, and i tried starter fluid as well, didn't help a bit. how integral are the o2 sensors in the tpi system, that wouldn't cause this would it?

 

In order to start is needs fuel, spark (at the right time), compression, and air. So you know it fires, but you don't know when. Do you have access to a timing light? That would be good to check (be sure to disconnect the EST when checking, see the article on timing). But if you haven't rotated the distributor, it's not the most likely cause. Also not likely compression because many cylinders would have to be bad for it to not start at all.

You may indeed have a bad ECM. It definitely needs it to run. You might also check to make sure one of the two wires on the injectors is getting +12V when the key is on. Since you have spark and fuel pressure, I would guess your injectors are not firing. You might want to pick up a "noid" light. It's a tester you connect to the injector harness to see if they are getting pulses to fire. They are pretty cheap and some parts stores may lend them out.

Good luck.

 

How wet are the plugs? May be a temp sensor problem. They have been known to fail, so, the computer thinks it is -40 degrees outside, and literally floods out the engine in short order. In really bad cases, coolant will wick up the wiring harness to the ECM, and corrode the terminals there..... If you have access to a scan tool, check what temp the computer thinks the engine is. Should be damn close to ambient temperature, with a cold engine.

 

the plugs are pretty wet, where is the temp sensor located?
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anyone else think its the ecm? i was gonna pick a new one up today, is it true the car WILL NOT start without it, because i heard otherwise.

 

without the ecm, the car will NOT run, regardless of what you have heard. The ecm controls the injectors, no ecm, no fuel, no run.

The temp sensor is on the front part of the lower intake manifold, screwed into the coolant passage, by the thermostat housing. Disconnect it, and check for evidence of a leak, that is a sure sign of failure. You can also check it with an ohm meter, should show some resistance, not sure of actual value, if it is open (infinite resistance) it is broke. The sure way to test it, is with a scan tool, and see what the computer thinks the temp is.

 

did you check ALL the plugs to see if they were wet or just one? the MAF and o2 sensors will not keep the car from starting.

while you are testing that temp sensor, test the resistance of the injectors while you are at it. they may be stuck open or closed hence why i ask about all the plugs.

i ran without my cold start injector in temp as low as 10*F without issue.

before you replace the ecm, check the fuse by the battery. i once had an issue where it would crank like crazy but not start. was the fuse. it's kinda doubtful since you have spark but might just in case.

 

I think the fuse by the battery is for the fuel pump..... that being blown would definitely keep the car from starting..

 

well, i picked up some parts today, a new ecm, distributor, icm, and cts. i also grabbed a fuel pressure gauge while i was there. tried to get a noid light for the injectors but they didnt have any in stock, so ill be picking those up soon. I swapped in the ecm, no change, so rules out that, tomorrow ill get to the other parts. BTW all the plugs were wet, not just one. Thanks for the help so far guys, ill check that fuse too just in case.

 

that fuse also supplies power to the ecm, not just the fuel pump. i've read more than one source(tgo being one of them) that the oil pressure switch will run the fuel pump if the fuel pump relay fails.

 

well, ive ran +12v to my diag. port already, and the fuel pump is running, im going outside right now to put in the new dizzy, icm, and cts, and im gonna check out the fuel pressure. hopefully i get somewhere.

 

well, im reading 40-41psi on the fuel rails during cranking, so im ruling out the fuel pump. Any ideas? Im doubting the distributor/icm will do anything, seeing as its getting spark, but i just wanted to rule it out. What else could be preventing it from firing up, when cranking, you can hear it trying to start.

 

Yep, not the fuel pump. How many miles on it? Have you removed or rotated the distributor? I'd say either the injectors are not firing (plugs wet?) or something is up with the timing.

 

I had the same syptoms that you discribe and unplugged the advance timing wire. trying now to figure out where to go from there. Mine never wouldn't start though. Ohhh yeah it wouldn't start when my VATS went out. That sucked.

 

well guys, i havent been out for a while cause its been snowing and miserably cold up here in eastern pa, but things seem to be warming up and i got out to my car yesterday. I hate to see the tuned port go, but i can't get the thing to start for the life of me. I'm not mechanically uninclined, but im at my wits end, i feel like ive tried everything. My friend suggested it jumped timing, hence why i just picked up a new dizzy a little while back, i figured if i was gonna pull it out and check it out might as well throw in a new one. but it was too cold for me to stick my finger in the spark plug hole and find TDC, lol, my finger was numb before i could feel anything. So, i was throwing around the idea of just pulling off TPI setup, throwing on an AFPR, carb and intake, and saying screw it. So i started the project of pulling off the TPI, but when i pulled off the plenum, i noticed a bunch of vacuum lines we all suffering from some severe dry rot under the plenum...but quite honestly i dont know what this stuff does, as ive never had to deal with it before. What is under the plenum? and whatever it is, would it not being hooked up cause a no-start? Im really rethinking pulling the TPI off, as its why i bought the poor IROC in the first place. If anyone can help me with what hooks up where, I believe the thing in the back under the plenum near dizzy is the FPR, but i dont know what the thing directly under the plenum is. Any help would be amazing guys. Maybe someone with a similar setup could take some pics or if anyone has pics, of the TPI setup up close so i can double check all the important stuff.
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also any help trying to find TDC and how to check to make sure my timing chain hasnt jumped would be great, i never really dealt with that either. BTW, i know this stuff is kinda TPI related and i dont wanna **** off any mods, so if this seems like it should be in the TPI section, feel free to move it, i just figured id get a little more help in this board.

 

The round guy under the plenum (in the middle) is the EGR valve. It should not make the car not start.

If you suspect the timing chain, pull the distributor cap, and turn the crank until you see the distributor start to move, then, turn the crank the other way, and see how far you have to turn it before the dist. starts moving. I believe that up to 8* was "acceptable", according to GM, more than that, and it's time for a new timing set.

Were you ever able to come up with a Noid lite? A test lite will work in a pinch.... at least, to verify if you are getting injector pulse.

While you are playing with the timing chain, turn the crank so the hash mark on the damper is at 0, see where the rotor is pointing, should be at either cylinder #1, or, #6. If it is way off, you may have an issue.....

 

never could source a noid light for it, none of the local auto stores have one. id have to buy one, and as for the timing, as of right now the dizzy is out of the car, and i bought a new one so i dont have the original timing marked, cause im a retard, lol, so i have to put it back in, is there any way to find out if it jumped timing with the distributor out? and tips on finding TDC and getting the distributor back in?
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also, i have test light, and hooked it up, and its showing i have power, but it doesnt flash for the injector pulse, which i dont think it can, maybe im wrong.

 

You need the distributor to check the condition of your chain, also, since you removed the dist., there is really no way to determine if the chain jumped. Once you get one in there, you can check chain tension the way a detailed above, that will give you an idea of the condition of the chain, and perhaps give you an idea if it possibly jumped time. (it would have to be REALLY sloppy to jump a tooth....)

To find TDC, pull the drivers side valve cover. Turn the crank until the timing marks line up at 0, and both valves on #1 are closed. Should be it. Or, pull the spark plug, put a finger over the hole while you turn the crank, when you feel air pressure coming out of the hole, line up the timing marks, and you should be good to go.

 

seriously thank you ploegi, lol, ive been lookin for another way to find tdc cause its so cold out i cant feel my fingers after bein outside for more than 5 minutes, lol. on the harmonic balance, theres the yellow line that i line up, but which of the marks on the timing pointer am i supposed to line it up with? any idea about the test light flashing a pulse or do i need a noid light for that. also, does anyone have and close ups of their tpi setup so i can see where all the wires and vacuum lines run? i know im asking alot, so thanks to all those throwing in their help, its greatly appreciated.

 

I hate working out in the cold. I want a car that only breaks down/needs work when the sun is shining, and it is better then 60* outside....... I am going to hold my breath until I get one! (that never worked for me as a kid either, nor did it work for my kids. Dammit.)

On the timing pointer, the deepest groove will be zero. Start there, and once it is running, use a timing lite, and set it where it needs to be.

Test lite should work, I think..... Keep in mind that you will have to use BOTH wires from the injector connector, the ECM grounds the circuit to fire the injectors, so, there is ALWAY 12 volts on one of the wires when the key is on. I suppose, you could conceivably determine which one is ground, stick the test lite in that one, and clip the lead from it to a power source? Whatever works best for ya I guess.

Dont have a digital camera that is worth a damn.... sorry bout that. There should be a vacuum hose routing diagram under the hood somewhere though.... I think...... Maybe, perhaps...

 

didnt think that test light would work, heard somewhere else the pulses were too quick to see, but i could be wrong. youve been a huge help, can't wait to get out tomorrow and get somewhere with this thing. might as well start strapping on the snow suit and mittens now, lol.

 

I am really unsure on the test lite, having never tried it, I was able to come up with a noid lite..... worst case, it doesn't work.... the bulb may only flicker a little, due to the short pulse, and the time it takes for an incandescent lite to wake up, but, if it does ANYTHING at all, it will be informative.....

 

guess ill just make a new post in the tpi section so maybe i can get some pics of the tpi system.

 

Well, i dropped dizzy in on TDC, i believe i did it right, the rotor should be pointing between cyl. #'s 1 & 8, straight towards the nose of the car right? But the part that confused me, is it supposed to be facing that way as im dropping it in, or after it turns when its seating? How do i go about double checking the timing now to make sure i got it right?

 

help.........anyone? lol, j/k, take your time guys, its freezing outside. just bumpin my thread.

 

Man no offense to anybody but everyone says do this or do that. okay you have to start at square 1. do a compression test... that will tell you right there if you have jumped time or if you have a mechanical problem. all cylinders should be around the same compression within 5-10psi of each other ,and should be around 120psi on a 305 tuned port motor. start there!!!! you shouldn't rip out the tpi especially without doing this first.
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it should point to the #1 pin on the dist. cap after you drop it it in and it seats IE the gears mesh together.if not pick it up and spin the dist. It's much easier to do with the rotor on the dist

 

I'm having the same problem but out of a carb motor. The dist is right at TDC, all the plugs are firing, plenty of gas. However, all that it does is crank and try to start at certain points as long as I have someone else turning the motor. Which I don't understand because three weeks ago the car ran perfect. I turned it off and didn't have a day off work for 3 weeks and went to start it thursday night and nothing. I have tried everything, checked all my wiring, timing, made sure the rotor was turning, coil, cap/rotor, turning the distributor. It is backfiring so would the valves be too tight, would that keep it from starting, i was running 110 now I am running 93 is the only thing that I changed in the three week period.

 

hey i'm actually in hamburg.....i would be more than willing to come out your way and help out....however little help i can be since i don't have much experience with these cars....but in about 3 weeks (income tax check time) i'll have an 88 iroc tpi which (should) be the same setup....if you don't have it fixed by then maybe we can rip mine apart for pointers....assuming we can remember how to put it back together in working condition lol

 

that would be great, hopefully its fixed by then, all our snow just melted from our last snowstorm, so hopefully I can get somethin accomplished. keep throwin out ideas guy, much appreciated. btw, I had already done a comp. test, everything was good and well within specs.

 

Have you changed the fuel filter ever?

Ok I just saw that fuel pressure is good while cranking....

 

hey astro i'm scheduled to pick her up on monday....so next week sometime if you would like to meet up or possibly the weekend following this one we can get ur car back on the road....i hate to see a car sit LMAO....pm me and i'll shoot ya my number if ya like

 

picked up a noid light set yesterday, gonna go out today and check it out.

 

ok bud here's the pix you asked me for yesterday

 

and some more

 

so i was out working on her today, picked up a new maf, but im in the process of hooking everything up that should be hooked up. i have another thread about that if anyone wants to try and help. anyways, i was playing with the noid light kit and cranked the motor and got no signal to the lights, but i dont have my intake plenum on, does the ecm send signal to the injectors when its not started or does just the CSV work when starting? any ideas? btw, thanks 3gjunkie, been busy, havent seen you online in like two days, ill catch ya eventually.

 

yeah i been busy too....lol...i'm still laid off and it's driving me nuts so i've been around lookin for jobs....i'm sure i'll be on when you are eventually

 

well i have everything hooked up now, i have signal to the injectors, 17 ohms or resistance all around the injectors, fuel pressures at 42 psi, i have a good spark, new MAF...but all im getting is a backfire out of my intake, which im guessing is from my timing being off, but i thought i had done it right. i had the distributor out, pulled the drivers side valve cover off, turned the crank to zero, everything seemed ok, but apparently i effed something up. can anyone help me out? I feel like im so close, but im at a loss for experience in setting timing. All the wires are definitely on right, so its not that, if someone could walk me through the whole process and where it should be and what i need, it would be awesome.

 

i also read something about pulling a wire when your setting timing?

 

anyone?

 

It sounds like your timing is still off. I would guess when you lined up the marks you were 180 degrees off. A quick check is to swap all the wires on the distributor cap to exact the opposite side. If it runs, you'll know.

 

That only works if you are 180 out. He could be anydistance off. You need to get it back over to tdc #1 on compression stroke. Install the distributor so that when it is fully seated the rotor is pointed at #1 terminal on the cap. Install the wires. Yes, you need to unhook the tan/blk wire over by the airbox on the firewall, to set initial timing. This really wont matter much until the car starts though.

 

well, after a long time, she finally purrs again,thanks to everyone who's helped, I've learned a lot.

 

So what was the cause of no start???

//RF

 

guess it was mostly timing, no idea why it took me that long to figure it out, but i hadn't noticed the cap moving or anything and the chain didn't jump, so i dont really know how that happened, my old MAF was bad too, when i plugged in a new one it idled smooth and ran great, i guess it was a combo of the two. i can finally move on to bigger and better things, amen. im lookin at getting the car painted now, black on black, then stickin in a t5 will be my next hurdle, i've never swapped from an auto to manual before, after i get that down smoothly, im already saving up for a lt1/t56 combo, its like looking a a blank canvas now instead of a giant question mark, lol, i can't wait.

 

well, guess i was close, but no cigar, it fires up fine now, but dies unless i feather the throttle lightly and dont rev it, or it sounds like its flooding, i was playing around with the distributor turning it, trying to get it to run better, but didnt really see any results, in what kind of increments should i be turning the dist., also, do i need a timing gun to aid me here, and what is the factory timing supposed to be at? do you guys think this is all timing, or something else, thanks for the help.

 

any suggestions/input regarding the timing?

 

It makes it alot easier to do the timing with a timing light. I am not sure on yours but my 91 rs is supposed to run at about 10 I think. You shouldn't have to turn much to adjust your timing. One way to raise it the other to lower it. Sorry can't be much help. But please let me know how this proceeds.

 

I believe all thirdgens by factory setting is at 0 degrees base. I would start at about 4 and work around from there, see what it runs best with.

 

ugh, i swear im gonna blow this car up, i have the timing set, im positive its right now, but the car idles for a few seconds, only stays running if i feather the gas, and won't even think about revving over 2500. anyone want a new car? lol, sooo...any ideas what i should do from here?

 

That sounds like a big vacuum leak. I hate to say it, but I think you need some help. A mechanic or a knowledgeable friend with some diagnostic experience and tools.