lets start with the basics..86 tpi in a 57 chevy.with painles harness..ran fine ..went to track ran ok on way home started stumbling a bit..not bad..has now progressed to runs terrible after its warmed up..pops backfires cuts out stumbles basically shuts momentarily off then takes off ok then shuts down..light flashes when it runs bad...no codes!!!..i have replaced pick-up coil in distributor..then ignition coil,cap,rotor..checked tps ok fuel press. ok..runs ok cold but the warmer it gets the worse it runs.............help!!!..i'm at a loss..on what next...all connections are good..when warm if you floor it it will hit about 2-4 grond then shut down then recover about 1500 then up again.......any ideas?

thanks
max

 

ok if i disconnect the blk/tan timing wire it run without cutting out..when i reconnect it..it starts cutting out?????????? any ideas
max

 

Possible ESC and/or knock sensor issues. You can temporarily bypass the KS by installing a 3,900 ohm resistor in its place.

Has it been running well otherwise since the timing tables and fuel curves were tweaked? I don't rememgber disabling the DTCs, either, so you should be getting all the standard error codes if they are generated. I know I opened up the MAF error tolerance a bit, but that's all.

Does it run just O.K. when cold, or completely normally?

 

runs normal when cold..the light flashes when it acts up but displays no codes...only acts up when it warms up and seems the hotter the car gets the worse it runs...does it when free revving or under load driving..car ran great up till this problem

 

if it was the ks would it shut it off like this tho?..i thought it would only retard the timing not shut it off?..just a thought

 

What chip are you running? Where did you get the ECM from? And do you know it is good? Usually, a flashing service engine light with no codes is due to the following.

1.wrong chip.
2. bad ECM or cracked solder joints in an ECM.
3. the chip not seated correctly in the ECM.
4. bad connection at the ECM.

Below is from a GM tech bulletin.

Some control module's may have problems due to cracked solder joints on the circuit board. These internal control module problems can cause the following symptoms:

Failure to start or vehicle is stalling.
The "CHECK ENGINE" "SERVICE ENGINE SOON" or "MALFUNCTION INDICATOR" light will flash or light up, but no trouble codes will be present.
Vehicle instrument panel displays may be inoperative.
The control module may or may not communicate with the scanner.
Other intermittent driveability problems.
Incorrect PROM or MEMCAL removal and replacement can create solder joint problems or aggravate an existing condition. See PROM or MEMCAL INSTALLATION for proper procedures.

 

That's a possibility, but all the sockets I use are Augat, high quality stuff. That, and the fact that the low profile sockets I use allow the cover to be reinstalled onto the CALPAK, helps hold all the components together. It wouldn't hurt to check to see that the CALPAK is still seated on the motherboard, though. While there, making sure the Painless connectors are still seated onto the ECM would be a good idea.

His BIN is working fairly well on quite a few other cars, so I don't suspect the code.

 

Any possibility to hook up a laptop to the car and see what the ECM is doing?

/N.

 

Correct me if I am wrong, if the timing gets to far advanced and the motor starts knocking the knock sensor will turn the SES light and go away when you back out the the throttle, right. My understanding is this symptom will occur with to much advance in base timing cause the ECM to advance timing to far at higher RPM.

 

Something like that is possible, and that's why I suggested the KS bypass with the resistor.

 

Thanks Vader, wanted to make sure of my understanding of the knock sensor operation.

 

Have you tried to move your MAT sensor to the fenderwell or somewhere where it wont heat soak to see if that would help? Mine read 135-160 when warmed up and driving(mix driving) when in the plenum. When I moved it to the firewall by the relays it read incoming air at (Basically ambient underhood air now) at 90-125 degrees. That makes a difference for fuel delivery. That is, assuming it is a fuel related issue.

 

vader,
where can i get a resistor to by pass the knock sensor?? midwest electronics?..what exactly do i need? thanks
max

 

ok replaced the esc module..no luck..and an extra ground quadruple checked my grounds..wha t happens if i in hook my knock sensor?

 

My understanding if you loose the knock sensor signal, will cause the ECM to operate the distributor (advancing timing)as if no spark knock is occuring, therefore not retarding the timing when and if spark knock occurs.
If it is unhooked, my guess is the ECM advancing the timing under load could result in the timing getting to far advanced, causing spark knock?? My best guess, anyone else try this?

 

Did you get this problem sorted? 'm having similar issues.

 

no i dint still chasing this problem...right now i'm messing with it..we arenot having fun..i dont know where else to search for the problem...everything had been replaced..all grounds good.....argh!!

 

I know exactly how you are feeling.

I'm trying to get hold of another ECM to see if that's my problem, which isn't too easy as I'm currently in the UK.

 

Have either of you tried an ohm test of all of your injectors? We did that on Momar's buick turbo and found 1 bad injector that had been giving him similar problems.