detination under part load
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New User
Joined: Jun 2003
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From: Red Deer Alberta Canada
detination under part load
I have a '91 explorer that i just finished doing cylinder heads on. The problem that i have ran into is that i have a detination problem under part load. If the unit is drove like grandma out for a sunday drive it is fine, but if you drive it in normal city conditions you get detination until the load drops off to a lower level. I checked for codes and found one for the ect sensor was out of range. This was the only code present. Like i said the heads were just done and all gaskets had been replaced and all hose reisntalled and clamped. there is no vacuum leak and all sensors have been tested. The resistance on the maf sensor seems slightly high on the signal side with a resistance around 8 Mohms resistance and the power side has a resistance of approx. 4000 ohms. the ect has been replaced. i had talked to a auto tech friend and he figures that it is just bad fuel. can't see that because i have refueled it and there is no power loss. I also run Bosch platinum plugs. anyone who can help would be greatly loved by my girlfriend. (I bought it for her to get around in)
Postmaster
Joined: Dec 2001
Posts: 3,742
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From: UT
detination under part load
Have you pulled the MAF sensor out and cleaned it? I've had a dirty MAF cause pinging in mine.
What was the nature of ECT code? Was it KOEO, KOER, or continuos memory? If KOEO or KOER, was the engine warmed up prior to performing the "quick test" (term manuals use for pulling codes)? Most of the time, and ECT code is a result of the engine not being warmed up for the test. An ECT that reads too hot can cause a lean condition and, thus, detonation.
How long have you had the Bosch platinums? Has it ever run well with them in? When I first got my '92 I replaced the Autolite coppers with some Splitfire plugs and the engine pinged like it was going out of style. Replaced the Splitfires with Autolite coppers and the ping went away. I've only heard the occasional anecdote like this, but some say that, if the engine was built for copper plugs (stock plugs in '91 and '92 explorers were copper core plugs) use copper plugs. Occasionally the lower resistance that platinum plugs have is enough to cause an engine to ping.
What was the nature of ECT code? Was it KOEO, KOER, or continuos memory? If KOEO or KOER, was the engine warmed up prior to performing the "quick test" (term manuals use for pulling codes)? Most of the time, and ECT code is a result of the engine not being warmed up for the test. An ECT that reads too hot can cause a lean condition and, thus, detonation.
How long have you had the Bosch platinums? Has it ever run well with them in? When I first got my '92 I replaced the Autolite coppers with some Splitfire plugs and the engine pinged like it was going out of style. Replaced the Splitfires with Autolite coppers and the ping went away. I've only heard the occasional anecdote like this, but some say that, if the engine was built for copper plugs (stock plugs in '91 and '92 explorers were copper core plugs) use copper plugs. Occasionally the lower resistance that platinum plugs have is enough to cause an engine to ping.
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New User
Joined: Jun 2003
Posts: 13
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From: Red Deer Alberta Canada
detination under part load
the plugs were put in when the heads were replaced. i have talked to the previous owners and they have said they didn't have a problem with detination before the head failure. the test was performed with the engine warmed up completely. thanks for the advice on the plugs and i will give it a try. it could be the same situation as the new triton engines and ngk plugs. thanks again. the maf has been cleaned. i will keep in touch about the
situation.
situation.
Posting Guru
Joined: Apr 2003
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From: West Chester PA
Did you just spray the MAF with cleaner, or did you scrub it? My explorer had a really bad ping. I sprayed the MAF and it still pinged. A week later, I took out the MAF and very carefully scrubbed it with an old toothbrush. The ping was gone. In the process of searching for the cause of the ping, I also torqued the lower intake, replaced the EGR and DPFE sensors, and de-carboned the cylinders with PM-3. Each of these things helped a lilttle, but scrubbing the MAF was what cured the pings completely...
Good luck!
Good luck!
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