Hi, I would like to get some people's opinion on my problem or who may have had similar issues. Here is my problem: Car will start and run ok when cold. Revs (in park) fine up to around 3k rpms (I haven't tried higher when its cold) but when it starts to get warm i will rev it up to about 2k rpms and it will sputter around for a second and die. When i go to start after wards it usually goes, but its a very rough lengthy start. The warmer the engine, the worse it seems. NEW PARTS INSTALLED: plugs (all gapped correctly.. changed plugs twice - same problem), wires (all connected to correct spots I.A.W. haynes diagram), cap, rotor, module, coil... Fuel pump/strainer, fuel filter, Air filter, cleaned IAC, seafoam through TB, 28oz of lucas fuel sys cleaner in tank. I've removed the TPS and it moves fluidly with no sticking. I have NOT however ohmed out the injectors but they all click properly during engine run. Also I installed a new coolant temp switch and thermostat. I have solid state ign. timing. I'm sure that i am forgetting a few things, but any help would be greatly appreciated. Thank you

 

I'd ohm out the temp sensor or better yet read the value with a scanner if you have access to one.

 

I'm going to change the cool. temp sensor today. On that note, i've heard that after the engine gets warm, the fuel supply depends on the oil pressure sending unit output. Does anybody know if this is true?

 

I'ts not true. The OP sensor will run the FP if the FP relay fails (hot or cold).

 

Update: changed cool. temp sensor, oil press sender, cleaned TB and intake.. same problems.. worse now - when its warm it'll start, run smooth for a few seconds, then sputter around 2 hundred rpms and die. Please help i'm out of ideas! Thank you jv9999 for your reply on the sender. Already changed the part hah.. oh well it was in bad cond anyway. Also on the update: I ohmed the injectors today and they were all between 8-16 ohms, which is close to the range in my haynes manual.

 

Is the SES light coming on? If so, have you checked the trouble codes?

 

the cel comes on after the motor dies, i don't know if thats normal or not but I cannot go anywhere to have it read

 

You don't need to take it anywhere.

https://www.thirdgen.org/service-eng...ht-error-codes

It's normal for the light to be on when the ignition is on and the engine isn't running. Wouldn't hurt to check, though.

 

Thank you, I will check that on my next day off. In the meantime if anybody has any more ideas on the issue, input would be greatly appreciated.

 

I checked for a code during my lunch break today, and none showed up. Any other ideas? Like I said before, it runs good when its cold (except if i hold it at 3k rpms it'll shut off), and when it gets warm it'll get worse to where it'll die at 1800 rpms and then when i go to start it, it will idle good for a second or 2 then surge around 200-1200 rpms and die. Going to start again takes a while and sounds very rough and it will die in same manner. Anybody have any more ideas? it has new plugs, wires, cap, rotor, module, coil, fuel pump, strainer, air and fuel filter, pcv valve, cool temp switch, oil pressure sender, fuel/tb/iac injection cleaning. no vaccum leaks noted, injectors ohmed good. Also the plugs were all gapped properly and because the problem started after the plug change, I changed them twice - same problem.. all the wires are connected to right plug/cap location. one other thing, when i rev it up to the rpms i said, it'll stutter around there like a rev limiter is there.. 3k when cold, around 2 when warmer

 

I also have a 1991 Formula and it had similar symptoms. Cold-start ran fine, but would run progressively rougher as the car warmed up. Eventually it would barely rev and then would die. Turned out to be the injectors and after I replaced them the Formy runs great! Good luck with yours! B

 

Have you watched your fuel pressure as it dies?

 

I'm having identical problems with my '90 Formula, and pulled the injectors last night. They all ohmed out good, but I have been told that is not a guarantee, especially on the '90-92 units, that they are shutting off mechanically, as they are notorious for causing exactly this problem. I will have them checked out under pressure and let you know what I find out.

TA

 

thank you all for you timely responses. i have yet to monitor the fuel pressure, this is something i will be doing in the near future. that is interesting on the injectors, i would be very happy to hear the results of your pressure test TA. Thanks again

 

Hey, out of curiosity, did you ohm out your injectors prior to replacement? if so did they ohm good?

 

with the engine running look at the spray of fuel comming out of the injectors

it should be a fine mist

while it is hot check the spray as well

 

I would like Jamon8 to explain how to look at the injector spray while the engine is running on a TPI car. That is quite a trick.

I did remove the entire fuel rail, and hooked to the fuel supply, turned the key on and watched (no wires attached) 2 of my injectors dribble fuel at an alarming rate, and 3 others just ooze. They all Ohmed out OK.

This is an unreal deal on a full set of 8 fine spray injectors for our cars, and this company is apparenly a 3rdGen.org sponsor as well.

http://www.southbayfuelinjectors.com...a3dlh2tj9fu836

I have to wait for them to come from the east coast, but the price is sure right.

Good luck
TA

 

Wow, that almost seems too good to be true. I've tried to research this site a little bit, but on every search engine I try the only result for the company name is their site, no reviews or anything. Maybe they're new or something.. I just dont want to get scammed or anything. Anyway thank you for your information on the pressure test, I'm going to try to get some new injectors and throw em in!

 

sorry for some reason I was thinking throttle body w/2 injectors

here is some tpi advice

while the engine is running take the injector terminals off one at a time

if one injector is bad it could effect the whole side

 

Sorry, but I didn't ohm them. I had the fuel-pump replaced just prior, but that didn't help. Popped in new injectors and "pow!" the engine started, idled and ran smooth as butter...

 

Just curious did you replace the O2 sensor?

 

if you are on a budget

we all are

and can not afford a set of new injectors and only want to replace one or two

while the car is running disconnect the plug at the injector one by one

if it does not run very well then unplug the injectors one at a time and try to start it

make sure that you put the injector plug back on before taking of another

if the car runs better without the injector pluged in then presto replace that injector

ohming is great but tells you like half the story

 

Hey guys. It is not TOO

 

HI ALL! Just want all of you to know that we are a very reputable company, no scams! And no the prices are not too good to be true! We are trying to get our name out there! You said it the best, you really never heard of us, well we are trying to change that! Our injectors will fit the TPi rails without any milling or modifying we guarantee it!

www.southbayfuelinjectors.com

 

Hey everybody, I didn't know there where any more responses because it wasn't notifying me in my email for some reason. I just recieved my injectors yesterday from southbay and they all look nice and clean. I will install them on my next day off and see if it fixes the problem! Shinobi'z, I did not change the o2 sensors. Also I ran it yesterday and its running rough cold now too. But anyway, thank you southbay for quick shipping and the price!

 

Our pleasure!!

 

Hey Guys...
I have been having similar problems with my '90 Formula TPI. One day the car just died on the freeway and had to have it towed home. Once home I checked for trouble codes and was notified that it was an EGR malfunction. I replaced the EGR valve and it seemed to be a little better but not fixed. Then I replaced the EGR solenoid and that didn't help. While it was in the garage and half apart, I threw in new plugs, wires, cap, & rotor--no help. I also replaced the fuel pump with a high flow fuel pump & Vortech FMU since I've been having a lean condition on top end ever since I installed a Paxton supercharger years ago. I just went through several vacuum lines and replaced them. It idles very smooth when cold and revs to redline (in neutral). Once it's warmed up, it idles a little rough but does not die. Once in gear and moving it surges if left in one gear at a constant speed and then it tries to stall. If I run it all the way to redline under part or full throttle condition in gear, it pulls through but as soon as I let off, it stalls. I disconnected the MSD Boost Timing Master to see if it was causing any issues but it runs more or less the same with it disconnected. Now when I check for trouble codes, I don't get any. I do however notice that my air/fuel ratio gauge is going berserk when it's running poorly. I have not checked the injectors (stock, so they're 19 years old), will go out and do that tonight. Whatever the problem is, it's nothing that the computer is tracking and therefore not something it can help me diagnose. I continue to think it’s EGR related, like if a passage is blocked, but then I remember that the computer tracks EGR function and has not flagged the EGR as a problem. However, it ran fine prior to the EGR malfunction code.

Any help would be greatly appreciated as I have been trying to figure this one out for months. Good thing this isn’t my daily driver.

 

So after pulling the plugs to the injectors (one at a time so I didn't mix them up), I got some interesting Ohm readings:
#1 - 11.7
#2 - 16.1
#3 - 16.2
#4 - 5.1
#5 - 13.6
#6 - 16.3
#7 - 16.4
#8 - 16.5

These were taken cold.

When I tried to start the engine after plugging all the injectors back in, it wouldn't start. It acted like it wanted to but just sputtered. I pulled off the #7 injector plug after noticing the rubber gasket inside fell out. When I reinserted the plug, the engine fired up. I let it run for a while but now it would instantly cut off like the ignition was killed...no stumble, sputter or anything, just off. I could go fire it back up again and it would run for a few minutes, then cut off again. After a few rounds of this, it wouldn't start again.

I figured I'd check the injectors again now that they were a bit warm and noticed some readings that were worse than before.

I rechecked a few of them (the easiest to reach) including those with the bad readings.
#1 - rechecked at 2.4 from 11.7 cold
#3 - rechecked identical to when it was cold at 16.2
#4 - rechecked at 5 from 5.1 cold
#5 - rechecked at 7 from 13.6 cold

I pulled the "bad" injector plugs when it was running and didn't really notice a change except for #4. When I pulled that plug, I noticed the idle was slightly rough.

I've been reading about the engine stalling when warm but now it's stalling when cold. Could this still be a sign of faulty injectors?

 

HI
I'm not a big knowledgeable guy with injectors.
But I am a fairly logical kinda guy.
Looking at your figures tells me that you have what seems to be 5 good injectors and 3 suspicious acting injectors.
How does the motor act when you pull off 1 of the 5 with similar ohm readings?
I'd expect it would be like pulling the spark plug wire, Only you are merely removing a different component which causes the explosion in the cylinder, Fuel. I'd expect it to run rougher with 1 of those removed.
I'd expect it to keep running tough. Even with a little more idle it would still run rough.
I don't know enough to advise on the shutting off though.
Perhaps trying a spark tester when it dies to see if spark has temporary failed.
That's what got my carbed engine diagnosed.

Hope I am of help.

 

Hey everybody, installed the new injectors and it runs strong and doesn't die! But this has uncovered a few new problems... High idle hot and cold (2-2.5k rpms) no vac leaks noted, occasional misfire (like before), and when i rev it say to 3500rpm, it will sit there and take about 8-10 seconds to return to the (high) idle. Any ideas?

 

have you tried setting your IAC and TPS

 

The iac and tps are both in good shape and i reset the connectors going to them no luck

 

http://sethirdgen.org/minair.htm

http://sethirdgen.org/tps.htm

try this and repost

please

 

I fixed the problem today.. the brake booster vac line was disconnected, i feel like an idiot ha but oh well

 

hey is it normal for our engines to operate around 240?

 

Yes, i had the same things happening to me.. good readings... stalling when warm, injectors fixed it.

 

no actually if you want the computer to read everything well then it should stay around 190-200

lower if you get your prom reprogrammed

 

Two things here:

1) It shouldn't run that hot if one fan is running is running continuously. At least not all the time. The first questions is "is your gauge accurate".

2) 240F not really bad, but getting there. The ECM turns on one fan at 221F and a switch in the block turns on the other one at 243F. So "normal" is somewhere around 225F for stock motors. 250F is time to shut it down. Someone wired on of yours to always be on. You need to straighten out the fan wiring and make sure the other one comes on.