87 tpi 305 t5, new engine, new ecu, fuel pump, maf. Replaced ect, esc module, distributor module, set tps, in plugged o2 sensor with no change to how it runs. The car starts ok, drives like an under powered camaro(normal for the 35's from what I'm told) but then after about 3 minutes or so, it just looses all power... Idles ok, but just no ***** under load at all. Fuel pressure is good, and it is so consistent that I can drive it to work(only a mile away) and it starts acting up within a block of the same spot every time. Even on the way home it acts up in the same block. I'm running out of ideas, but I had someone tell me it sounds like the timing is off when it is running poorly. But when it runs ok, it sounds fine. Once it starts running poorly, it will not quit until you turn it off for quite a while. Also fuel pump is new and I have access to just about any part I could want to swap as long as the 350 part is the same

 

It sounds like it could be timing. If your saying it feels "weak", like it doesnt have the power it should, that could be timing. It may idle ok (or seemingly ok) but unsder load is a whole different story.

I believe (someone correct me if im wrong) in 85 is when the timing is controlled by the ecm. Im still used to timing my '81 fbird(converted to non-CC), which is quite a bit different than our TPI cars. I remember reading that base timing should be 0-6*, and if i remember right it said "the lower the better". If im right about what ive said so far, i would check the base timing, and maybe play with it a bit (trying each degree,0-6) and see if you get any difference.

Something else you may want to consider, look over your ingition system. Check the terminals and posts in the cap, check the plug wires for corrosion in either ends' boots, arching, ect. If your car hasnt had an ign. system tune up in a while, try throwing a cap, plug wires and plugs at it. If you have a 350 laying around these parts will swap over. Even if this doesnt fix it, it still wouldnt hurt.

Also, double check, then TRIPLE CHECK that the FIRING ORDER is in the correct order!!! I caught myself switching around two wires, ran ~ok~ under idle but real pathetic under load. This may be your problem. Its actually a very common problem, and very easy to mix up.

 

Check the coil, pickup coil and base timing. If its a TPI car base is 6deg. Make sure you unplug the tan white stripe wire on the rear of the pass strut tower to set the base timing. Its like the PIP on ford stuff..

 

any codes?

 

All tune up parts are new, the car runs well at cold start, and it's misfiring. Base timing is 6 btdc. Firing order has been checked a billion times. I can replace the coil or even the distributor if it may help.... Unless the balancer slipped, base timing is correct, but it seems odd that it would run right and then stop after a few minutes.

 

Maybe a bad PROM or a sensor? Your description sounds like it is fine until it warns up & goes into Open Loop, which would point towards a sensor, if not the PROM itself.

 

Have you ohmed the INJs ??

Edit: I think 87s had a better inj so you may be ok there but check anyway.

 

 

what are the 35s' supposed to mean?

 

305's

 

Ecu is brand new. I will ohm injectors tomorrow. I can't think of any sensors that could cause this that I have not replaced.

 

Weak fuel pump! If not, bad cat. Weak fuel pump will make it backfire. Is the check light on?

 

You know what, it's people like you that start **** on these threads by your rude comments. I was asking a simple question. What are 35's? Uh, that could mean anything. A 305 is generally referred to as a 305 or a 5.0 , not a 35. Mind your own business as I was not asking you obviously.

 

ok ladies, enough drama for one thread, anyway, THATDAVIDKID sounds like when the engine heats up it loses power. I had the same problem on a carb'd engine. I lowered the under hood temp and it helped considerably. I could be way off but its just an idea. Good luck man.

 

Check for codes first. Sounds like your knock sensor is bad or came disconnected. Check codes first..

 

No codes

 

ohm your fuel injectors yet? Check the timing? THose are the two i would worry about right now.

 

I'm off tomorrow. The timing has been set to 6 degrees. I will also re check that. What is normal for timing at idle with the wire connected? Wonder if something is making it retard timing after it warms up. As far as the codes it HAD. had a maf code once but that was because I didn't clear after I had it in plugged. Another time it threw a lean code while it was acting up, after I replaced the maf, that code did not come back. As for the "35's" in the first post, that was a typo, it happens...

 

It really sounds like injectors, the ninth injector will add fuel for cold startup but when the timer switch warms up it will turn off. 35's those are some mudder's you got on that 4x4.

 

Now that makes sense... What is the best place to buy injectors? They're something like $60 each at a part store... Are they high impedance or low impedance? I know fox body mustangs have high impedance 19's, and I can get those cheap.

 

http://www.southbayfuelinjectors.com...tors_More.html 19#hr bosch 3's for a lb9 you get a 10% discount for being a tgo member.

 

I've seen bad injectors causing the exacty symtoms you described. You also could have gotten a bad new part and have multiple issues.

 

The parts I've installed are all known good parts. I'm hoping its the injectors, only because I'm ready to find the problem.

 

The only thing that isn't a good used part is the ecu, it was brand new from gunn chevrolet(I guess maybe factory reman) in San Antonio. I've worked at a few dealers and I've never gotten a bad ecu.

 

be sure to check the injectors both cold and hot.

 

Have you replaced the CTS for the ECM (not the gauge)?

Ohm checking the injectors is not the whole story; they can still be leaking/dripping fuel and test ok for ohms.
Pull the intake elbow in front of the TB, then open the throttle blades and smell for gas inside the plenum (indicating leaking injectors, torn FPR diaphragm). Pull the vacuum line from the plenum to the FPR and smell inside for gasoline (indicating a torn FPR diaphragm).
And when you get new injectors...use South Bay as mentioned above...

Hope this helps.

 

There are no fuel leaks, fuel system holds pressure well, ect for computer is new. All 8 injectors ohmed out at 16, going to check for vacuum leaks while the engine is warming up before I do the hot injector check.

 

Didn't find any vac. Leaks and injectors ohmed out exactly the same.

 

ECT is the same as the CTS...(coolant temperature sensor, located in the front of the intake manifold), I get it.

Can you do any data logging, maybe we can see a pattern there...I have used WinALDL and a home-made ALDL cable to data log.

Hope this helps.

 

Ect sensor and "cts" as you call it are the same if you're talking about coolant temp... Engine coolant temp sensor...

 

Also forgot that the previous owner had injectors flow tested and cleaned before he re installed them.

 

It seems to be a closed loop sensor issue...and the best way to find it may be to use a scanner/data logger. There are some nice options out there, for the budget minded you can build an ALDL cable (via Radio Hut) and WinALDL...

Hope this helps.

edit: Thanks for the corrections/info regarding ETC:CTS, never done learning...

 

I would def look into restricted cat or exhaust system. Also check o2 sensor. If its stuck rich it could be leaning the mixture right out causing lack of fuel. It SHOULD throw a code (i think its a 45 but dont quote me) but I have seen them go bad and not throw a CEL before. Also check fuel press regulator too. If its only off idle, It could be bleeding down. If you are still on timing issues, unplug the timing connector (tan/blk wire) and see if its any different. By disconnecting that you will cut ECM control out of system. May ping but may also help you narrow some stuff down. But It really sounds like restriced cat to me.

 

It feels JUST like a restricted cat. Only problem is it doesn't have one. I removed the plenum and runners, capped off every vacuum line except the fuel pressure regulator and brake booster, re installed plen and runners with new gaskets, will see tomorrow I guess. Going to reset valves tomorrow too.

 

One thing I noticed is the driver side runners don't long up right on the base side, but it appears to be the flange was misaligned when it was made back in 87.... I imagine this is not my issue because the car was driven regularly for 25 years...

 

My old ones were fine cold, lousy hot. Make sure you do them hot.

 

I checked them after the sound of the engine changed( that's when it starts acting up) and they were all at 16 ohms.

 

have you done a sweep of the tps ?

 

Yes

 

Your describing a very common problem I'm surprised no one has suggested the EST module in your distributor. It is by far the only intermittent failure piece of these EFI engines. If your parts store can check it have them do it three times, if any one fails well theres your sign.

It also need heat conductive compound underneath it to distributor plate and the screws that go through it also ground it. So clean them up.

If your issue is that consistent then make it happen and put a timing light on it and rev engine to see if it starts to fail or does weird things to timing. HTH!

 

I changed that the other day...I will put the timing light on it tomorrow after I get the exhaust welded up.

 

Do you know anybody with a scanner, (it has the added benefit of data logging)? You can buy an ALDL cable inexpensively (or build one for very little) and download some free software (WinALDL, TunerPro), this gives you a scanner that can monitor all of the sensors on your car. Once you have this, start looking for a sensor value that is "stuck'" ie. never changing.

I was able to build an ALDL cable in an afternoon and start datalogging that night.

I hope this helps.

 

I'm guessing I will need a laptop? I have a pc laptop but it is really crappy. I'm planning on putting the OTC Evo from work on it tomorrow, but I have a full schedule so we'll see.

 

Excellent, I needed an older laptop with an RS232 port, but it really is a very handy tool. If your willing to wait a few days, you can get a USB ALDL cable (much better than the home-made variety).

Good luck.

 

I re adjusted my valves and then put the exhaust back on. The car still isn't quite right, but it is now drivable. I have a major exhaust leak near the manifold, but I'll drive it some more tomorrow. Also filled it up with good gas, almost 12 gallons so I'm sure the gas will work now. It now just feels like the timing may be a bit off so I'll re do that after I fix the exhaust leak.