Alright here we go...

My car was originally a DPFI car, I did the 4 injector and OBD1 swap.

I'm running a chipped and socketed p28.

When the car gets hot it would miss at first then it will miss REALLY bad at low rpm with heavy throttle and just gets worse and worse.

To the point yesterday the car died when going through a light that just turned green.

I had a spare dizzy that i swapped in right on the side of the road and it seemed to fix it.

I drove another two hours and found the same thing happening.

It seemed to me that it would start to happen at low rpm and get worse and higher RPM and lighter and lighter throttle to the point where the car would completely die if I went WOT at low RPM and if I nursed it to like 3-4k rpm I could go WOT.

It died on me again so i thought maybe its a heat problem and i tried to swap out the dizzy to the other one. nothing still did not fire.

swapped ECU with another and nothing.

listened for the fuel pump and I hear it prime.
I hear the main relay click.
Car has 245K on it.
Fuel filter is relatively new.
Gas was low but not empty. (1/8 tank)

Finally I got it to run after an hour of messing with it on the side of the road with the dizzy that failed the second time by moving it all the way to full advance...

and even on the way home from that the car would still miss and stumble and it was getting worse and worse in that short drive (10mins).

thank you for any help...

 

Also just checked mechanical timing, it is correct.

 

do you see any smoke when the car does misfire?

 

yes there is black smoke and popping when it misses.

 

i have seen a few cases where the engine coolant temp sensor grounds out when it gets to a certain temp. when it starts missing and popping turn the car off and ohm out the coolant temp sensor on the cylinder head. if it is the case i believe those sensors are about 15 bucks

 

If you worked with the fuel injectors, I hope you changed the o-rings under the valve cover while you were at it. If not, that could be why this is happening.

 

innes887: thank you, i will check that today.

five5: if i had the fuel injectors out what would that have to do with having the valve cover off? as far as i remember the valve cover does not need to come off in order to change injectors.

but in any case i did the valve cover gasket 6 months ago and there is no oil in the spark plug tubes.

 

Possible weak fuel pump. Was it running fine before the mpfi/obd1 swap?

 

is was running fine before the mpfi swap.

i changed the dizzy and that seemed to fix it although i have yet to drive it very far.

ill keep you posted.

 

drove it for ten miles today and it seemed to act the same as before only not nearly as bad: missing at low rpm popping and backfiring.

im at a loss.

 

ttt

 

any CEL's? my car did this and it was the igniter. you said you swapped dizzys though...

 

no codes at all...

 

hmm...check the ecu ground on the thermostat housing?

 

ive fix the problem, when i swapped the dizzy i just unbolted the cap and swapped it over, i didnt bother to see if the wire are tight on the cap. i checked the cap the other day and the wire were loose... i looked inside each wire tower and i saw burning so i bought a new cap and cleaned the wires and the car runs awesome again!!

thanks for all of your help guys!!