Hey every one just after some advice of where to go next. 1991 Z28 350 tpi. When its cold it runs ok. Please forgive my explination if i get it wrong. When the choke/ cold start turns off she runs like a sack of sh*t impossible to drive, revs up and down no more than 1200 rpm at a peak and drops to a stall then it stalls and wont start then runs bad. until its stone cold again then its all good. Have done distribuator/ rota arm/ filters/ fuel filter/ plugs/ leads vacume hoses all the hoses i can see anyway. it seems to run lean as if its being flooded with air and starved of fuel but fuel pressur seems ok. Any help or advice or just say have you tried this your obvious might not be mine. many thanks guys.PS: its not throwing out any codes

 

I wonder how your coolant temperature sensor looks. I would measure the resistance of it on a cold motor. There is a chart around here that show the proper resistance versus temperature.

 

Is that the same as the engine temp gauge excuse me if it may be a stupid question

 

It is not the same as the sensor for the gauge. It is right below the thermostat on the engine.

 

ok i will take a look. if i disscconect it will it think its constantly cold? and therefore run with the choke still on ? im not great with electrical stuff. Many thanks

 

There is no "choke" on a tpi car. The computer just compensates for the temperature. If the coolant temperature sensor is telling the car that it is a t a different temperature, it won't run properly. When mine went, it wouldnt idle hot.

 

Ok thanks could that also stop it from driving aswell? This sound highly possible and im wondering if it could be the fact that its running a speceal heavy grade coolant?

 

my car has been doing the same exact thing. Turns out, it has bad fuel injectors, which is common for stock TPI systems.

Get your hands on an Ohm meter, and measure the resistance in each injector when cold and when hot. Before you start the car when its cold, unplug the injector wires and place a lead on each of the metal prongs on top of the injector. Measure and record each injector.

Repeat the process once the car has warmed up, preferably once its hot and stalling out. Let us know.

 

A very good suggestion.

These old injectors have been having problems with the ethanol in modern fuel.


The injectors should have higher resistance than about 12ish when hot. They should also be fairly balanced.

 

Hi, Just checked the injectots six are at 17.5 ohms and one at 4.3 and the last is 3.4 but this means nothing to me.

 

If I can remember correctly, that is too low and those two injectors need to be replaced.

 

Do i have to remove everything down to the fuel rails to get them out?

 

+1.

That is most likely your problem.

 

Depending on which one it is yes. if it is injector 1 or 3, 6 or 8 i think you might be able to loosen the bolts that hold the rail to the lower manifold and then lift it enough to get the injector out of the bung and off the rail. the others are a little more tricky because they are hidden by the runners.

 

It would prolly be worth your while to replace them all as I seem to remember the later years injectors being problematic. Also remember to bleed off the fuel pressure, you should just beable to follow the instructions for changing a fuel filter. Don't need to get fuel in your eyes or all over your engine bay.

 

Thanks guys tomorrow i will start pulling it down and let you know the outcome

 

Well after waiting for the parts to come from Rockauto the Camaro is back on the road again and running sweet. It was worth the wait though as there nearly $200 each in the uk. Thanks for all the advice guys......

 

+1 to that, my 1991 T/A with the 305 TPI has been doing that. Bad injectors as well, probably because the car's been sitting for a year before I got it.