wierd stalling issue. starts back up immediately

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May 3, 2013 | 07:15 AM

massiveB

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From: dedham ma

wierd stalling issue. starts back up immediately

ok guys, im gonna pull codes after work today, even though the service engine light isnt on i hope it stores something. first off the car is an un modded lt1, auto, longtubes and x-pipe mated to stock mufflers, no other mods. maybe you guys can point me straight.
the engine runs great,no misfires or anything. it acts the fool in 2 circumstances. not every time, but frequently, when i launch heavily, either from a stop or a rolling start, i get a hesitation/buck (feels to me like spark cut out), falls on its face, a quick back fire and then it takes off like normal. never completely quits if im moving.
the other circumstance is i'll be idling great at a traffic light, either just sitting, or just starting to takeoff, it just straight up quits without any idle hunt or roughness, just like a snap of a finger, it dies and will start back up immediately (as soon as i get over the flusterred embarasment of stalling and holding up a green light to get it in neutral). it hesitates for a second or 2, then goes about its normal business. i've searched and found a couple threads describing a similar situation, but none have posted any resolution. any ideas, or shortcut diag tips will be appreciated thanks - bob

May 3, 2013 | 08:41 AM

jmgtp

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Does it do it hot and cold or just hot? I had a bad ICM that caused somewhat similar problems. On a cold start it ran fine. Once it heated up the problems surfaced. The ICM is bolted to the passenger side head and gets heat soaked. It should be on a aluminum plate with heat disapating grease sandwiched between the ICM and plate.

Check plugs, wires, ICM and coil first. Don't jump right to the opti just yet.

May 3, 2013 | 10:42 AM

lt4obsesses

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From: H-Town Texas

Also check your fuel pressure regulator, it will cause this as well.

May 3, 2013 | 03:37 PM

massiveB

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From: dedham ma

thanks, i guess it really has only done it when its hot. didnt really notice that but now that i think of it, doesnt do it unless ive been on the road for a while. ill check icm first. plugs and wires are delco and not too old, few years old, but mileage wise only about 5k on them

May 4, 2013 | 04:50 PM

massiveB

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From: dedham ma

replaced icm and ignition coil today with delco parts, seems to have cured problem. i'll know for sure tomorrow after i drive it longer. but so far so good. i think the problem was the heat from the new headers did the icm paste in. it was pretty crusty looking. the coil looked like the original from 92 so i swapped it while i was there, had to drill out the rivets (felt a little silly after arguing with the parts guy that the coil/icm was a 1 piece unit, not separate) but not a big deal to change either or both.

May 20, 2013 | 07:31 AM

massiveB

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From: dedham ma

just to update, the coil and icm, as crappy as they looked, did not fix my problem. its starting to happen more frequently now, hopefully that should get the diag moving along quicker. hooked my fuel guage up and have confirmed it is not a fuel pressure issue. starting to look opti-ish. i went through the service records and found that just before i took ownership the water pump was replaced, im wondering if leaking coolant may have spoiled the opti spark. just wierd that its a dead cut-out, i would expect more of a misfire condition with a distributor issue, no?

May 20, 2013 | 08:28 AM

lt4obsesses

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From: H-Town Texas

Quote:

Originally Posted by massiveB

The intermittent troubles are the worst. In diagnosis, you have to catch it when its acting up, like fuel pressure, for example. Perhaps take a look at your grounds, ther are three. There is the engine ground, a braided strap wire going from the lower left bellhousing bolt to the frame under the battery. There is the chassis ground, also bolted to the bellhousing on bolt up from the other. Then there is the battery to engine block ground, just in front of the bellhousing. I imagine they are similarly placed in an automatic.

May 20, 2013 | 11:06 AM

bjankuski

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From: Glenbeulah Wi

I suspect you need a tune. The headers are flowing more air and you are getting a lean tip in as a result of the additional air flow. The 1992 are a SD computer and they are touchy when modifications are performed. This should be easy to fix in the tune with both VE changes and accelerator enrichment changes.