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Hi: I'm new to this forum.... Anyway, I having a problem with my 1991 Chevy 2.8 V-6 and was wondering if anyone out there might have a few ideas.
The engine is actually in a Jeep Cherokee but the engine is set-up as a stock ?91 S-10 with all the ECM electronics and emissions. Over the years I?ve added Edelbrock headers, a mild SpeedPro cam, and a Holley 502-3 400 CFM TBI. I?m running WinALDL and have used the TunerCat R/T Tuner to dial-in the set-up. Things seemed to be working fine?. But, I do spend quite a bit of time out of the area where the Jeep is so it?s been in storage for the past 6 or 7 months. Well, I?m back with the Jeep and now having an issue with it.
Anyway, the problems are: warm idle and warm restart. The engine runs fine usually, but when warmed-up, it idles fine for about 3 or 4 minutes, the idle then gets really rough, and finally the engine dies. It often won?t restart then until I let it sit for 15 minutes or so, then the whole thing can be easily repeated, time and time again.
First thoughts where fuel filters? Installed new ones; not the problem.
Next, fuel pump? Checked out OK, plenty of fuel to the TBI, even when it won?t restart. It just cranks.
A few things I?ve noticed are:
- O2 readings are normal just before the engine dies. The Rich/Lean counter in WinALDL is also incrementing nicely. Then all of a sudden the O2 readings go way low (after about 3 or 4 minutes of idle), the idle roughens and the engine dies. Even when I try racing the engine when it starts to get rough I can?t get the O2 reading back up and the engine to run properly. It?s like the ECM just doesn?t want to give the engine fuel. I?m not running a heated O2 sensor, but it seems to hold accuracy fairly well, even when idling. The ECM is in an Open Loop mode at idle anyway ? not using BLM?s - so it?s not supposed to be using the O2 readings anyway. I just use the O2 as a point of reference.
- After the engine dies and won?t restart I noticed that while cranking the fuel injectors in the TBI aren?t firing. The fuel pump is still supplying fuel though. It? seems like the ECM has decided not to give the engine any fuel.
My guess is that the ECM has some kind of ?Clear Flood? that it thinks (or) is occurring and is trying to clear. In WinALDL the ?Clear Flood flag/Not Closed Loop? flag sets about a minute after start-up and stays set throughout the remainder of engine operation. It coincides with the engine going into closed loop/BLM mode for the first time and stays set until engine shut down. Unfortunately I think the programmers of WinALDL lumped the two flags together for my ECM and I have no easy way of knowing if just a ?clear flood? situation is occurring. No other flags or errors are being set coincident with the engine going into this lean condition, roughening, and then stalling.
Anyway, any thoughts would be greatly appreciated.
The engine is actually in a Jeep Cherokee but the engine is set-up as a stock ?91 S-10 with all the ECM electronics and emissions. Over the years I?ve added Edelbrock headers, a mild SpeedPro cam, and a Holley 502-3 400 CFM TBI. I?m running WinALDL and have used the TunerCat R/T Tuner to dial-in the set-up. Things seemed to be working fine?. But, I do spend quite a bit of time out of the area where the Jeep is so it?s been in storage for the past 6 or 7 months. Well, I?m back with the Jeep and now having an issue with it.
Anyway, the problems are: warm idle and warm restart. The engine runs fine usually, but when warmed-up, it idles fine for about 3 or 4 minutes, the idle then gets really rough, and finally the engine dies. It often won?t restart then until I let it sit for 15 minutes or so, then the whole thing can be easily repeated, time and time again.
First thoughts where fuel filters? Installed new ones; not the problem.
Next, fuel pump? Checked out OK, plenty of fuel to the TBI, even when it won?t restart. It just cranks.
A few things I?ve noticed are:
- O2 readings are normal just before the engine dies. The Rich/Lean counter in WinALDL is also incrementing nicely. Then all of a sudden the O2 readings go way low (after about 3 or 4 minutes of idle), the idle roughens and the engine dies. Even when I try racing the engine when it starts to get rough I can?t get the O2 reading back up and the engine to run properly. It?s like the ECM just doesn?t want to give the engine fuel. I?m not running a heated O2 sensor, but it seems to hold accuracy fairly well, even when idling. The ECM is in an Open Loop mode at idle anyway ? not using BLM?s - so it?s not supposed to be using the O2 readings anyway. I just use the O2 as a point of reference.
- After the engine dies and won?t restart I noticed that while cranking the fuel injectors in the TBI aren?t firing. The fuel pump is still supplying fuel though. It? seems like the ECM has decided not to give the engine any fuel.
My guess is that the ECM has some kind of ?Clear Flood? that it thinks (or) is occurring and is trying to clear. In WinALDL the ?Clear Flood flag/Not Closed Loop? flag sets about a minute after start-up and stays set throughout the remainder of engine operation. It coincides with the engine going into closed loop/BLM mode for the first time and stays set until engine shut down. Unfortunately I think the programmers of WinALDL lumped the two flags together for my ECM and I have no easy way of knowing if just a ?clear flood? situation is occurring. No other flags or errors are being set coincident with the engine going into this lean condition, roughening, and then stalling.
Anyway, any thoughts would be greatly appreciated.
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