I have a 91 Formula 350 TPI the car runs good until around 3800 RPM. It acts like it starts dieing out like it has a clogged fuel filter. I have replaced the distributor, cap, rotor, plugs, fuel filter, plug wires, and O2 sensor. It seems to run better but did not fix the problem. The timing is set correctly and the SES only comes on when I drive for several miles at interstate speeds. When I turn the car off and start it again the light is off. If anyone can help I definitely would appreciate it. The car is completely stock.

 

Start there. Does it always do that? Whats the stored code? Sounds like an EGR code though.

 

Maybe it's the fuel pressure regulator.

 

Sounds like I may be having the same issues, mostly when cold, still noticable hot but not as much.

91 Z, 305 TPI, auto.

Car doesnt seem to want to shift at more than half throttle when cold, just stops accelerating and has no power. Less noticable when its warm, but still there.

Replaced plugs, wires, dist cap and rotor, O2 sensor, etc ....

Getting a code for an O2 sensor lean. I installed one of the Painless Wiring fan switches that kicks on at 185* and off at 170* (I think those are the right temps), is this causing the O2 code to come on and if so, how do I fix this? Do I need a PROM re-program? It also only comes on after a few mins at highway speeds.

Other code I have been getting is an EGR code, dont remember which one. Could and EGR problem be causing my problems?

 

I will replace both this weekend. I have not tried to pull a code yet but i will be doing that before this weekend. Thanks for the advice.

 

What? I didnt give out any advice or in any way say you should "replace" anything .... I think you mis-read my post my friend.

 

Anyone out there?

 

I am new here I didnt mean to put your reply in my reply about replacing the items. I am willing to take advice from any of the above because I am willing to get my car running right. I was referring to the fuel pressure regulator and EGR valve. As to mis-reading your reply I didn't and I hope this clears things up!

 

Eh, no problem.

Anyway, I have a hard time believing that an EGR fault could be causing this. Anyone else have other ideas to check out?

 

I just got through putting on an airfoil and cold air kit. When I took the car for a drive I felt a differene in power but with the open air cleaner I heard a popback when I reached 3800 RPM. Could it possibly be a worn timing chain?

 

no offense but, it sounds like you've got your firing order off to me my friend unless of course your fuel pump is dying out, thats hte only things that would cause it to go that lean imo, unless you have a stuck shut injector or 2.

also if your car was maf make sure u plugged your maf back in i didnt pay that close of attention to year, if it was the speed density tpi ignore this part.

if i were u #1 i'd check and c what that code is, #2 check fuel pressure, if 1 and 2 r found to be ok then you can start determining a messed up firing order or bad injectors

 

I checked the firing order and it is correct. I will check the rest tonight. Thanks.

 

I also know the firing order. And fuel pressure is where it should be.

 

Anyone else have ideas?

 

I just pulled the code from the ecm. I am getting a code 32. EGR
Could this be causing my trouble?

 

my buddies 89 gta does the same, and has the same code, we found a intake vaccuum leak and it took care of it, don`t know though if that`ll work for you but thats my idea. timing chain is a thought but that would normally afect the idle to.

 

Thanks, I will check it out.

 

No vacuum leaks, no codes. Fuel pressure is good, changed the fuel filter and ignition coil. Anyone have other ideas?

 

bump

 

I just changed the EGR and fuel pressure regulator. The car idles smoother but the problem is still there and the same as before.

 

I've heard plenty of people say that even disconnecting your EGR will not cause driveability problems.
But the code after running at highway speeds for a while does sound like an EGR thing.
Sure there aren't any vaccuum leaks somewhere?

 

Bump, someone has to have other ideas on what to check here, or have had the same issue.

 

I got rid of the EGR code. I am leaning toward the fuel pump or possibly one of the cats stopped up. I will give an update when I get the fuel pump replaced. I can hear the pump whining after I get off the highway and let the car idle for a sec before cutting it off.

 

Have any updates Dewey? I changed the Coolant temp sensor today, seemed to smooth things out a little bit, but the original problem is still there.

 

Does this only happen behind a load, or does it also happen when your idling in Park, raising up the idle speed with your hand...?

 

Provided your fuel supply is adequate, and is holding enough pressure throughout RPM, I'm leaning toward a faulty ignition module. That is, unless it was already changed with the replacement distributor that you listed above (if I'm reading the above installations correctly)....

 

It happens in park and with a load on it. Sorry it took me so long to get back on here I have been sick and taking an easy for awhile. I am in the process of getting another block from a friend that came out of a 91 to build a 383. I plan on using my heads and an edelbrock intake and runners.

 

I had a similar problem with my car. Search for my post.
It would act like it is hitting the rev limiter.
Mine would cut out at 4500.

I put in a msd distributor and it fixed the problem. I believe that it was the ignition module. Did u change that?

 

I changed it when I changed the distributor. I am planning on taking the car to a mechanic that I know and trust to put in a new fuel pump. I am getting one that will handle the 383.

 

I am at a complete loss. I have replace the distributor, cap, rotor, plugs, O2 sensor, egr valve, and Map sensor. I have also replace the fuel pump, filter, and regulator. On the exhaust I have replace both of the cats and muffler. I have also replace the TPS and set it to .54 volts not running with the switch on. I have checked all the injesctors with a ohms meter. They all read between 14.2 and 16.5. There are no codes in the computer. The car still chokes down around 3800 RPM. I cheked all the ground wires on back of the head leading to the body and the ECM.

Is there any possibility that the ECM is going bad? Or does it sound like there may be a problem with the lifters floating out or the valve springs are weak.


Any help would be greatly appreciated.

 

Oh yeah I forgot to add that I double checked the firing order, rechecked the timing with the est disconnected at 6 degrees. There are no vacuum leaks either.

 

Update. I had to remove the engine due to a leaking freeze plug on the back of the block. I discovered that the engine was not the factory motor. It turned out to be a reman TBI truck motor. The motor had 193 heads and the camshaft was a factory truck roller cam with around 380 something intake and around 412 exhaust lift. The rocker arms were also way too tight. The computer could not compensate for the difference and was flooding the engine at WOT. I have purcahsed a new cam and lifters from comp, a new set of patrior vortec 185 heads, and a stealth ram. I will give an update when I have the motor back in and running.

 

UPDATE. I have finished the enigne build and installation. I used Partriot Vortec Heads, Edelbrock TPI Vortec base and a comp 08-300-8 cam. The car runs fine and it solved the problem that I had. Thanks to everyone for their help.

 

I have nothing useful to contribute, I just thought the title was kinda funny... you know you drive a TPI car when you call 3800rpm "high RPM"

That is all.

Carry on.