enginecry

I'm really trying to love this car...

89 Formula, 350 TPI. Bought the car with a "won't start without starting fluid problem" got that fixed (bad injectors) but now it runs fantastic when cold and like hell when hot. It consistently misses. Spark and injectors check out. It happens quickly, within 1 - 2 miles. After researching the threads, I read that it changes from closed to open (or vice versa) when reaching regular operating temp but that doesn't mean I understand. Here's the list of new...

Fuel pump, TPS, IAC, wires, plugs, cap, rotor, MAF relay, ICM, 22.5 injectors, fuel filter, EGR valve, IAT sensor, Oil pressure sending unit, CTS, coil and probably a ton of other stuff I've forgotten about. It doesn't throw any codes.

I'm really at my wits end with this car, I'd leave it in Detroit with the keys in it but I don't want to stick a thief with these problems...Help me please. Can I send cash to whoever helps me find the answer?

Theking

iTrader: (1)

I have similar problem like you do, runs great when cold and the longer it runs the worse it get, running richer and richer and backfiring when i rew it up to maybe 3000rpm on Parking.. Check all the thing you have, I also made an compressiontest, vacuumtest they engine is like new in the values.. so i dont understand whats the problem is..... The thing is , its not always backfires and so.. sometimes it runs pretty good.. the worst thing is : Having problems when I have a gear in like D or [D] and holding Brake at stoplight.. it tends to go down in rpm and sometimes it will backfire when i rew it up on idle... its really enoying, its almost chokes it self, sometimes its down to 450rpm... (as the idleairscrew is) and its starts to shake and rumble... If i put it in N or P it goes up to 750rpm and stays stable... thats so strange.... what can it be that making it run bad when in gear and holding the brake ??

My other thread : https://www.thirdgen.org/forums/tech...asetation.html

5ltrbtr

Have either one of you checked you timing.

Theking

iTrader: (1)

Base timing 6 degrees.
havent checked with the ECM connected.. had to put som timing tape on for checking the hole timing. but the base is 6 degrees...

5ltrbtr

open and closed loop refers to when the computer is actually using the measurements from the oxygen sensor to determine if the engine is running rich or lean. if the sensor is saying lean then the comp. tries richen the mix, and if the sensor keeps saying lean then the comp. keeps going rich and vise versa. hope that clears it up enginecry

Orr89RocZ

iTrader: (20)

o2 sensor?? do you mean when the engine is cold it runs fine, or do you mean when its cold outside lol? when the engine is cold it runs off the ecm and doesnt read the o2 sensor. once warm it goes into closed loop and reads the 02 sensor. if its a bad o2 sensor, it will run poor/rich once it gets hot enough.

redfire82

heck. unplug the sensor and give it a try

enginecry

Orr89Rocz - engine cold not cold outside, could rich mimic "missing"? My timing is set at 6 degrees. You say when hot enough...how hot? The car does run very, very hot. Even more than 210-220. Needle is usually pegged after 15 minutes or so until I cool it down. I thought this (overheating) was an additional problem to be fixed later alongwith, hatch, headlights, wheel bearing noise etc. Could this overheating be an additional symptom? God, I hate this car....

enginecry

Picked up an o2 sensor on the way home and it ran Great!!!!!!!!! until it got hot... Any help would be appreciated!

Theking

iTrader: (1)

ehat brand on the o2 sensor ? heard that any other brand than AC Delco will mess things up... I will buy a new AC Delco O2 sensor and see if it helps..right know I have Standard Motors o2 sensor... maybe thats crap....!..

I will try with an AC Delco sensor instead...

Orr89RocZ

iTrader: (20)

i have bosch and my car runs fine.

when i said hot, i mean like when the o2 sensor heats up and the car goes into closed loop...something like when the coolant reaches 140-150degrees.

your overheating problem definately needs to be fixed. it shouldnt run super hot all the time. try replacing the thermostat to a lower 180 degree unit or so. Flush the radiator. Check to be sure your fans are coming on.

As far as it missing, i dont understand why it would once it got "hot" and entered closed loop. Running rich and poor in closed loop may mean you have a bad MAF sensor or bad ecm. If all the other sensors are good and your ignition components have been replaced (cap/rotor/coil), then it could be MAF related.

Else you have a bad wiring connection to the o2 sensor and the ecm is not reading the o2 sensor like it should

IROCThe5.7L

Are those new injectors in there? I'd test the ohms on each injector when the engine is hot to just make sure.

enginecry

The one code the car threw was a MAF relay code. I replaced the relay and it has not reappeared. The PO took the screens out of the MAF - could that cause the probelm? I don't think it is a rich or poor condition in closed loop, it is most definitely a "miss" but then again I'm not that bright.
----------
Yes, the injectors are new. 22.5 lb pink top bosch. What should the injectors meter out at? Is there an FAQ link for this?

Orr89RocZ

iTrader: (20)

i have the screens out in my car and it ran good for years and still runs good, well i have a problem now but i dont think its MAF related.

What do injectors OHM out at? i am curious to check mine out as well

enginecry

OK now I'm really worried if someone who has 5000 posts is having unknown problems.... Who can answer the injector ohm question AND is anyone going to take me up on my offer of a cash reward to solve this problem????

IROCThe5.7L

Orr89RocZ

iTrader: (20)

well i had ideas of what it was but didnt want to go into detail...i just ohm'd mine and i got atleast 2 dead injectors didnt bother checkin the rest cuz thats all i needed to know. Thing was tho, this problem only was at a certain point in thirdgear and alittle at part throttle in other gears, but not at wot. generally bad injectors bleed off fuel pressure at the rails, and my pressure holds fine. Also bad idles, rough running which i wasnt experiencing. Also creates hard starts which i wasnt experiencing so i wasnt sure what the problem was lol

WLD_Bill

iTrader: (1)

I don't understand? Did the problem get fixed or not? I read a long list of replies, then get let down with no answer. I feel like I'm in my car right now.

RodsRideSS

Have a good look at your distributor for misalignment between the reluctor and the magnet...as the reluctor sweeps past the magnet, the magnetic field triggers the coil through the module . If there is any misalignment between these two parts the spark occures off the dist post and only gets worse as the vac advance takes over. Check the alignment of the reluctor and magnet inside the distributor. Pull the cap, cut a slot in it so you can see the rotor at #1 post. Put it back together and pull the EST plug off the dist. Start the engine give it some RPM and aim a timing light at the slot...the rotor tip should be lined up with the post. If it's not, the magnet and reluctor are out of phase

enginecry

The problem never had been fixed. She is tucked away for the winter now though and I will resume in the spring. It is completely frustrating.
----------
I've always thought it was a timing problem but don't understand why it would only have this problem when it went into closed loop. If I determine that this is the issue, will a new distributor solve the problem. Every other ignition part has been replaced.

Theking

iTrader: (1)

Like I said earlier I had the similar problem, runned good cold and the longer I was driving the worse it got... missfired, smelled fuel and runned really bad, rpm went from 450 to 750rpm when holding brake and in gear at stoplight..

I GOT MY PROBLEM FIXED!
I had too high fuelpressure so when the engine got more fuel when its hot (ecm will give more fuel when its getting warmer "%enrichment" and so)
With 23lbs/hr injectors and a too high pressure the ECM couldnt compensate for that and it ran bad... got the fuelpressure right and the car runs like never before..

So. have you checked your fuelpressure ?.

Travis&camaro

I have the same problem with my v6 camaro. I have replaced coils oxigen sencer, maf, plugs wires, injectors, fuel pressure? I just dont know what it is. I'm thinking the valve's adjustment is off but.. Idk. Let me know if you guys figure it out.

WLD_Bill

iTrader: (1)

I located the problem. 2 injectors ohm'd out at 6 and 9 instead of 16 ohms like the others. When I unplug those injectors the car misses but it doesn't shut down at around 3000 RPM. Plug the injectors back in and it screws up again. Yea the car seemed to run really good when cold, but the ECM wiggs out after awhile then runs like crap. I will put in replacement injectors this week and post again.

enginecry

I have checked fuel pressure and it runs high with the AFPR. Even as far out as the screw will go, it still has 45 PSI. I did replace the injectors with 21 lb instead of 19lb. Wonder if that's the problem???

WLD_Bill

iTrader: (1)

Fixed. Replaced 2 injectors, engine runs smooth now. Now that the ECM is not freaking out anymore, neither is the speedometer! Speedometer was jumping, stopped working, sometimes worked, acted like a tachometer and a bunch of other weird stuff. Special thanks to Dokken10 for the replacement injectors.