88 cutting out while driving (intermittent)

[badabing9]

greetings,

strange problem here.
while driving even at a high rate of speed, i am getting an intermittent problem with my car cutting out (shutting down). it is only a momentary cut off at this time.
.......88 vette, 74k miles. new plugs, cap, rotor, ignition module (under cap), ignition coil, new fuel filter, fuel pump pick-up sock, electronic spark control module, both maf relays replaced.

i noticed before i had my first symptoms, that once or twice the car was idling in my driveway before i replaced the electronic spark control module (located at passenger side near heater box) the first time), that i would shut the hood and the engine would very noticibly stumble, almost shutting the car down.

approx 3 weeks ago, it was happening very badly. and i barely got the car home. thinking it was the coil, i replaced it and it seemed to idle fine. i decided for some reason, to lightly "tap" on the electronic spark control module and that caused a very noticable stumble in the idle as mentioned above. i immediately replaced it but, before i did, i monitored the fuel pressure and it remained steady.

the problem creeped up today again and i am going to replace the module again, under warrantee. could this be an iac problem?....it is throwing no apparent codes as the "ses" light was coming on as in a stall and the light went out when the car "came back on again". i believe it is an electrical problem moreso than a fuel delivery problem. any ideas anyone. the car runs great except when it cuts out for "microseconds" so to speak...........thanks all!

 

[WhalePirot]

With the stumbling happening when you 'tap', I'd carefully check the wiring at/to that module; see if it is moving and shorting out momentarily. I would expect such a problem to worsen, as yours seems to be.

 

[VQT]

Un plug the MAF sensor to see if the engine runs better. If it is, bad MAF.

 

[badabing9]

greetings,

thanks for reply.......i will unplug the maf to test however, i don't think that is the problem as the car runs fine except with that infrequent intermittant stumble (cutting off) i described earlier.

i thought i had it fixed, or at least was on the right track, when the car crapped out after light taps on the electronic spark control module where obviously, it should not have reacted that way with a few light taps.

unplugging the maf for testing purposes will make the car run horribly when it is running fine and, it will be virtually impossible to get out, open the hood and unplug it when it is only happening for less than a second or to.

also, the wiring and the connection(s) were the first things i check......anyone else with a thought?

 

[badabing9]

With the stumbling happening when you 'tap', I'd carefully check the wiring at/to that module; see if it is moving and shorting out momentarily. I would expect such a problem to worsen, as yours seems to be.

it has been a lot better then when i first experienced the problem a few weeks ago. since i replaced the module, it ran fine until the other day. however, the cutting out is very infrequent compared to what i had originally and and before i replace the module. the wiring and connection(s) were the first things i checked.

 

[VQT]

Do you know how to pull the codes?

This might be EGR relate issue, I am not too sure about your problem but mine had this stumble once but not as bad as you described. There are two things you should check, one is the sensor connect from the (EGR?) pipe. That pipe is connect to the passenger exaust(sp) manifold. The other one is the sensor that attach to the top of the thermostat and a vacumn hose to the EGR itself.
I didn't check it but replaced the sensor on top of the thermostat and the problem hasn't come back since.

 

[1stC3Vette]

What comes to mind is a possible intermittent ground connection. Is it possible that your connector is fine, but a wire off of the connector is not making a good connection?

Good luck,
Dino

 

[badabing9]

Do you know how to pull the codes?

This might be EGR relate issue, I am not too sure about your problem but mine had this stumble once but not as bad as you described. There are two things you should check, one is the sensor connect from the (EGR?) pipe. That pipe is connect to the passenger exaust(sp) manifold. The other one is the sensor that attach to the top of the thermostat and a vacumn hose to the EGR itself.
I didn't check it but replaced the sensor on top of the thermostat and the problem hasn't come back since.

well, i really hated to use the word "stumble" which seems to imply a "miss". the car is actualy shutting down as reflected by the "ses" light coming on and the loss of power steering such as in a non-computer controlled car. so, this would rule out the egr as to actually shutting the car off momentarily as the problem.

 

[badabing9]

Do you know how to pull the codes?

This might be EGR relate issue, I am not too sure about your problem but mine had this stumble once but not as bad as you described. There are two things you should check, one is the sensor connect from the (EGR?) pipe. That pipe is connect to the passenger exaust(sp) manifold. The other one is the sensor that attach to the top of the thermostat and a vacumn hose to the EGR itself.
I didn't check it but replaced the sensor on top of the thermostat and the problem hasn't come back since.

oops!, i forgot this part...........yes, i can and do know how to pull the codes and have an auto x-ray 6000. when it did this before (pulled codes), i had no codes on the scanner or otherwise that would drift me to the problem.

 

[badabing9]

What comes to mind is a possible intermittent ground connection. Is it possible that your connector is fine, but a wire off of the connector is not making a good connection?

Good luck,
Dino

i have thought of that. i have traced everything that i could and no luck. whatever it is, it seems to be "spark related" of sorts. like maybe the coil, or hot connection to same, or ignition module under cap, etc...however, i have replace all that.

today, i replaced the electronic spark control module (again, under warrantee)and it seemed to smooth the car out when i replaced it. i am hoping that i just got a bad module originally and this one is good. in each case, the syptoms of the 2nd bout with this are similar to my current bout . i am gonna cross my fingers and hope problem solved..

 

[BlackNBlue95]

oops!, i forgot this part...........yes, i can and do know how to pull the codes and have an auto x-ray 6000. when it did this before (pulled codes), i had no codes on the scanner or otherwise that would drift me to the problem.

If I am thinking correctly here, the ign. module is in the distributor, so are you tapping on the distributor? Maybe you have an pickup coil failing. The pickup coil provides the RPM signal to the ECM without an RPM signal the car will not run. If the signal is dropping out intermittently perhaps this is causing a stumble or dieing condition. this is just a guess as I am sure there are a million things that can cause this problem.
-=Rick

 

[VQT]

Can't help you much there. Go to www.corvetteforum.com for more help.

 

[Patio]

I have an '86 that had the same problem. It was an aftermarket throttle position sensor. After replacement with an AC Delco sensor everything is back to normal.

 

[badabing9]

I have an '86 that had the same problem. It was an aftermarket throttle position sensor. After replacement with an AC Delco sensor everything is back to normal.

THAT IS INTERESTING!...I HAVE BEEN THIUNKING THAT FOR A WHILE. I "BUMPED UP" THE ADJUSTMENT ON THE SENSOR AND MAYBE IT "MOVED". HOWEVER, I WOULD HAVE SURMISED THAT IT WOULD HAVE SET A CODE. I WILL RETURN IT TO A STOCK SETTING AND SEE WHAT HAPPENS. DID YOUR CAR ACTUALLY SHUT DOWN MOMENTARILY OR JUST STUMBLE, AS MINE ACTUALLY SHUT DOWN

 

[badabing9]

If I am thinking correctly here, the ign. module is in the distributor, so are you tapping on the distributor? Maybe you have an pickup coil failing. The pickup coil provides the RPM signal to the ECM without an RPM signal the car will not run. If the signal is dropping out intermittently perhaps this is causing a stumble or dieing condition. this is just a guess as I am sure there are a million things that can cause this problem.
-=Rick

there is an ignition module inside the distributor cap that was replaced. there is an electronic spark controll sensor that is about 2/3rd the size of a pack of cigarettes that is monted on or near the heater box at the firewall. that is what i "tapped" on and found to be eithr bad or "on it's way out. i will check the "pick up coil" as it was not replaced initially and could very well cause the problem. damn, i missed thjat in my thinking!....thanks!

 

[Patio]

It totally shuts down..., it also throws a code into the computer but I don't know what it is.

 

[badabing9]

It totally shuts down..., it also throws a code into the computer but I don't know what it is.

i see...mine hasn't as far as i know. however, today i "backed" down the tps a bit so it is well w/in limits. i have a new one coming anyway although, i don't think it is the problem but, worth fiddling with.

i will obtain the pick up coil" (so-to-speak) that was mentioned earlier for underneath the distributor cap although, i can't remember seeing one.

 

[badabing9]

greetings all,


anyone ever replace a pick up coil inside a distributor (88 vette)? is it hard?......does it require the distributor to be pulled?.....thanks!

 

[wishuwerehere82]

greetings all,


anyone ever replace a pick up coil inside a distributor (88 vette)? is it hard?......does it require the distributor to be pulled?.....thanks!

Yes, the distributor has to be removed. Once you get it out, the roll pin in the drive gear has to be driven out with a punch. The shaft slides out of the distributor body and then you can unscrew the screws that hold the coil and replace it.

 

[ProEMTPFF]

greetings,

strange problem here.
while driving even at a high rate of speed, i am getting an intermittent problem with my car cutting out (shutting down). it is only a momentary cut off at this time.
.......88 vette, 74k miles. new plugs, cap, rotor, ignition module (under cap), ignition coil, new fuel filter, fuel pump pick-up sock, electronic spark control module, both maf relays replaced.

i noticed before i had my first symptoms, that once or twice the car was idling in my driveway before i replaced the electronic spark control module (located at passenger side near heater box) the first time), that i would shut the hood and the engine would very noticibly stumble, almost shutting the car down.

approx 3 weeks ago, it was happening very badly. and i barely got the car home. thinking it was the coil, i replaced it and it seemed to idle fine. i decided for some reason, to lightly "tap" on the electronic spark control module and that caused a very noticable stumble in the idle as mentioned above. i immediately replaced it but, before i did, i monitored the fuel pressure and it remained steady.

the problem creeped up today again and i am going to replace the module again, under warrantee. could this be an iac problem?....it is throwing no apparent codes as the "ses" light was coming on as in a stall and the light went out when the car "came back on again". i believe it is an electrical problem moreso than a fuel delivery problem. any ideas anyone. the car runs great except when it cuts out for "microseconds" so to speak...........thanks all!

I was having the exact problem with my '86 and it was also "throwing a code BUT when I tried to get the code it would'nt flash for me. What it ended up being was the ECM "computer" had a few cold solder joints and I had to replace the computer.