92 B2600i runs great except when it doesn't
#1
05-24-2011, 03:23 PM
92 B2600i runs great except when it doesn't
Problem first noticed late last summer when temperatures moderated (nights in the 40-50's), truck would fire up and then die. A little extra throttle might keep it going but not always. On the 2nd or 3rd try it would usually keep running.
Then the weather got very cold, and the problem mostly vanished. The only lingering effect, every now and then just running along, there would be a hiccup, as if I'd suddenly let off the gas. These hiccups wouldn't last more than a second and might not happen but once every week or so.
Then the weather got warm and problems returned with a vengeance. The first time the problem happened after the truck was all warmed up, then stopped, and tried to start again (5-30 minutes) later. Raising the hood and allowing heat to escape seemed to help.
Lately I might be running along and all of a sudden no power. Put it in neutral and revving above 3000 rpm sometimes helps restore power.
Figuring a bad connection on some connector, I removed and replaced all such connectors near the engine. No help. It is difficult to see the problem happening when sitting and idling in the driveway, but I did today and just messing with the throttle, it would seem like opening the throttle did little or nothing - it mostly kept running the same speed unless I really "floored' it, and even then the RPM's might be 1/2 of what they should be for that throttle position.
So, given the lack of throttle response, I'm suspicious of the MAF sensor, which is an expensive thing to replace. But would a MAF problem cause issues for idling? Any recommendations for testing the MAF?
I've had the CEL light on since (exactly) 80,000 miles (now 85K), IIRC that's just a timed reminder to check the oxygen sensor. With the recent problems I tried to read the codes back by grounding the orange wire on the green connector at the passenger side firewall, but the CEL light would not flash. So either I've been grounding the wrong connector or the ECU is out to lunch.
Any suggestions before I waste money on either a ECU refurb or MAF sensor?
Then the weather got very cold, and the problem mostly vanished. The only lingering effect, every now and then just running along, there would be a hiccup, as if I'd suddenly let off the gas. These hiccups wouldn't last more than a second and might not happen but once every week or so.
Then the weather got warm and problems returned with a vengeance. The first time the problem happened after the truck was all warmed up, then stopped, and tried to start again (5-30 minutes) later. Raising the hood and allowing heat to escape seemed to help.
Lately I might be running along and all of a sudden no power. Put it in neutral and revving above 3000 rpm sometimes helps restore power.
Figuring a bad connection on some connector, I removed and replaced all such connectors near the engine. No help. It is difficult to see the problem happening when sitting and idling in the driveway, but I did today and just messing with the throttle, it would seem like opening the throttle did little or nothing - it mostly kept running the same speed unless I really "floored' it, and even then the RPM's might be 1/2 of what they should be for that throttle position.
So, given the lack of throttle response, I'm suspicious of the MAF sensor, which is an expensive thing to replace. But would a MAF problem cause issues for idling? Any recommendations for testing the MAF?
I've had the CEL light on since (exactly) 80,000 miles (now 85K), IIRC that's just a timed reminder to check the oxygen sensor. With the recent problems I tried to read the codes back by grounding the orange wire on the green connector at the passenger side firewall, but the CEL light would not flash. So either I've been grounding the wrong connector or the ECU is out to lunch.
Any suggestions before I waste money on either a ECU refurb or MAF sensor?
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