long and short of it, It cranks fine, runs.. but while im driving .. the engine just shuts off.. since i have it in gear it cranks itself right back up.. then runs for a while no trouble

Yesterday it did the same thing, except this time the check engine light came on, checked for codes got P0372... NOW.... i just replaced the opti spark 2 months ago.. what would cause the engineto just shut down.. and then let it sit for a second or 2.. and just crank it back up like nothing happened ?

thanks
Paul D. Marchiafava

 

It's dropping Hi res pulses from the distributor to the PCM. Causes are: open circuit, short to voltage or ground or a defective encoder inside the opti.

Did you connect the vent lines correctly?

Did you check the integrity of the pins on the opti and the harness?

 

yes to the first... and probably not to the second...


but on that note...why wouldnt i have had this problem from the get go.. and just start having it now ?

 

P0372 will not shut the engine down. The PCM will use the low res pulse pattern to set the igntion timing... it just makes it slightly less accurate. The code sets when the PCM sees 4 low res pulses without seeing a high res pulse.

Total shutrdown is more often related to loss of the low resolution pulse, which shuts down the fuel pump and injectors. Are you sure you aren't also seeing P1371 as a "stored" code?

Appears you have an intermittant loss of the signal(s). Could be corrosion or damage to the harness connectors....either the one at the Opti, or the gray one on the bracket on the passenger side of the intake manifold.

 

ok..now this is just a stupid question now...yesterday it was hard to start up.. but it ran all the way home from work with no problem.. just hard to start..

anyway... would a cloged fuel filter do this as well ??

and no to the low res code.. it defintly was the p0372 code

 

A clogged fuel filter will starve the engine when the engine is under load and fuel flow is maximized.... not necessarily uinder the low flow requirements of startup.

Check your fuel pressure. Extended start times can be due to the fuel system not holding pressure when it primes. That can be caused by leaking injectors, faulty fuel pressure regulator or bad check valve in the fuel pump. You want to check the fuel pressure after the pump primes, but before you try and start the engine, to make sure the pressure is not being lost quickly when the pump shuts down. Then check it at idle, and on the road under max load/max rpm.

Interestingly, a problem with the PCM finding the low res pulse will also cause extended start times, in addition to your sudden cutout under load, but the would be setting a code.

 

ok... tried to start it up last night to move it... and well.. just didnt start period

 

Scan it for codes and with KOEO check to see what the sensors are reporting. Reset the codes after making note of them and see if any return when cranking it up. The ones that come back, get to work on.

Just speculation but since you had a Hi res problem before, you probably have a low res problem now also. Both together would cause the no start condition.

Tell tale sign is the loss of injector pulses.

 

sorry its taking so long to post back, but i have yet to get around to working on my problem till now...and before i start ripping out the opti spark again...(which was my hi res problem).. can it be the opti went out again , and thats causeing my low res problem ?

I guess I just wana know what i should start taking apart before i got after that opti again

thanks

 

in fact, i have both of those codes on mine. i checked it on a tech 2 and my low fuel trims in both banks was dropping quickly, until it died. this was all in closed loop. my car runs in open loop almost all the time, now. if it switches into closed loop, it starves it for fuel and the computer switches it into open loop. car runs great in open loop. do i have a bad pcm or a also the same problem he is having with opti connections? thanks, sorry to be a thread stealer.