Hey guys..these TPI motors are new to me. I have a "flat spot" upon acceleration. And also...after sitting a couple days, it smokes a tad when started...seems to be running rich. My first idea is a TPI rebuild kit...what are your thoughts?
​​​​350/TH700r4​​

 

Assuming there is no check engine light, normally this is either a TPS sensor or a EGR valve issue.

 

Thanks Gorn. I'll check into it...could that also be a reason why it seems to run rich?

 

Possible, are you getting a rich code?

 

No check engine lite...haven't hooked anything up yet.

 

How do you know its running rich? How old are the O2 sensors? Normally if an engine is running rich and the ECU does not know it the O2's are shot.


I would plug the EGR and drive it to see if the flat spot issue goes away. You can also check the EGR for leaking, search youtube for testing a an ERG valve for leaking. Leaking EGR valve will cause the engine to run rich.


Other possible issues are the MAP sensor and low fuel pressure.

 

I bought this car in April of 16. I don't have any history on it as far as 02 sensor replacement...maintenance...nothing. The smog pump was removed at some point...but a plastic box and the hoses were still intact on the pass. side. They have since been removed and the hoses just folded over for now. I've put together quite a few cars during my lifetime...but this TPI is absolutely greek to me. I'll continue my research on Google and You Tube and anything you guys throw my way. Thanx!!

 

The TPI is just a basic EFI system. It is not much more complicated then a throttle body from the same time. You are kind of assuming this a a TPI issue. There is just as much chance it is not.

Assuming you plan on keeping the car I would do all the routine maintenance the engine needs so you have a starting point.

Plugs, Plug wires wires, Dis cap and rotor, check all the hosed for crack or rot, Re-torque the intake, fuel and air filters and last would be the O2 sensors. Also verity the Large intake hose leading from the Mass Air Flow sensor is in good condition. Remove clean and test EGR valve, remove clean and reset IAC motor, clean throttle body. (see you tube for the last three.)

When you are done check for vacuum leaks using some carb cleaner with the engine running.

I was a GM tech that worked on these cars through the early 90's. If you had brought me a car 5 years old this with no history this is what I would have recommended. If it is a TPI system issue having all that right will make the issue easier to find. I would guess about 1/2 the time when I was done there was no more issue. I have had many customers tell me that the car ran better then new, Course they are just forgetting how good it ran new.

A lot of times when I tell people this I get " the spark plug wires look good" or some other part looks good. I have thrown away a lot of very nice looking parts because they are bad. There is no good way to fully test a spark plug wire expect putting them on a scope with the engine is running. This test tends to cost more then the wires. I have seen detailers clean 10 year old wires and make them look new. 10 year old wires are 3 years late to the trash can.