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Check engine light is on?

Tiny
DENIDUME
  • MEMBER
  • 1992 TOYOTA PICKUP
  • 4 CYL
  • 4WD
  • MANUAL
  • 200,000 MILES
My 92 toyo 4x4s check eng lite comes on when eng. Temp usually reaches certain temp. Then it seems to misfire. No problems starting or running for about first 10-15 min. Light does go off when im coasting then returns apon exceleration. Did diagnostics and came up with airflow meter. Could it be eng. Coolant temp. Sensor?Temp gauge is staying about the 1/4 mark. Shouldn't it be at about 1/2? Very confusing. Any one with help they could give me. Thanks, Dennis in Olympia, Wa.
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Thursday, June 25th, 2009 AT 5:17 AM

31 Replies

Tiny
MHPAUTOS
  • MECHANIC
  • 31,938 POSTS
Hi there,

The check light is a visual indication that a set fault code has be set in the ECU, read this code using this guide and report it back here,

https://www.2carpros.com/articles/toyota-trouble-code-definitions-and-code-gathering-method-1990-1995

If the light is coming on during acceleration and then shutting off on decel, then that points to a fuel issue or a perceived fuel issue. So this means we need to inspect the fuel pressure and try and monitor the o2 sensor data.

Basically we need to know if it is running rich or the o2 sensors are telling it that it is running rich.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

You should be able to monitor live data on this PCM with most scan tools so let me know what the o2 sensor voltage is on accel and decel when the light is going on and off. That will give us a good idea as to what is happening. Assuming the fuel pressure remains steady we may want to just pull the o2 sensors and test them using this guide.

https://www.2carpros.com/articles/how-to-test-an-oxygen-sensor-02-sensor

It is odd that the light corresponds with the throttle so I am pretty sure we are going to find a fuel issue. Please run through this info and let us know what you find. Thanks

Mark (mhpautos)
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Thursday, September 5th, 2019 AT 12:15 PM (Merged)
Tiny
DENIDUME
  • MEMBER
  • 2 POSTS
I did a scan and the code came back as 31. Thanks, Dennis
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Thursday, September 5th, 2019 AT 12:15 PM (Merged)
Tiny
SERVICEDEP
  • MEMBER
  • 1 POST
  • 1992 TOYOTA PICKUP
  • 3.0L
  • 6 CYL
  • 4WD
  • MANUAL
  • 265,000 MILES
This truck will crank cold and run perfectly for usually one to three minutes, at which point the check engine lamp illuminates. When the lamp comes on the truck will hardly accelerate. It will also not self test while it is in this mode. If I let it cool for a while, it will self test and shows no trouble codes. When the check engine lamp is off it revs up fine. I have done a lot of testing and cannot find any components out of spec. I suspect the ECM but cannot find one anywhere. I have seen this same complaint on this forum from user 93Yota_Project, but no fix was ever posted. Has anyone else seen this and successfully fixed it?
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Sunday, November 15th, 2020 AT 8:43 AM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 42,882 POSTS
To me it sounds like the EFI relay is getting hot and failing the connection. Here is the location see if the relay is warm:

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Check out the diagrams (below). Please let us know what you find. We are interested to see what it is.

Cheers, Ken
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Sunday, November 15th, 2020 AT 8:43 AM (Merged)
Tiny
2CP-ARCHIVES
  • MEMBER
  • 4,542 POSTS
  • 1991 TOYOTA PICKUP
  • 380,000 MILES
Can an erg valve make a rattle noise (or fast poppinsound). Ou can feel it rattle when at an idle and on rpm drop when slightly reved Truck has had a ping when foot is held steady to maintain speed. But goes away if I lift off the pedal or apply more acceleration. Also when first started truck pings (rattle) very noticeably until check engine light pops on then goes away immediately is this due to needing a valve adjustment.. And what would make
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Sunday, November 15th, 2020 AT 9:18 AM (Merged)
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
First, what is the code?

It sounds more like a motor noise than egr.

Roy
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Sunday, November 15th, 2020 AT 9:18 AM (Merged)
Tiny
ADAMLICK
  • MEMBER
  • 1 POST
Well it threw a knock sensor code. Which I assume its a timming issue but its spot on before light comes on and after. And to clarify it has to totally different sounds. At idle its a dull or hallow and with a hand on the egr valve, or solid (one with rubber hose attached and a plastic back you can clearly feel it. Only when at operating temp when cold it just whistles. As for maintaining speed it sounds like a valve clearance issue, but wouldn't it do it all the time when at temp
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Sunday, November 15th, 2020 AT 9:18 AM (Merged)
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Egr has nothing in it to make noise.

What is the code?

Roy
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Sunday, November 15th, 2020 AT 9:18 AM (Merged)
Tiny
ROAMINGANT
  • MEMBER
  • 5 POSTS
  • 1991 TOYOTA PICKUP
  • 200,000 MILES
On my 91 Toyota pickup 22re, I just replaced the exhaust manifold gasket, and my check engine light came on. Pulled my plug wires and got good rpm drops for all. Truck wants to stall almost like Eddie Murphy's banana in the tailpipe (beverly hills cop). Could a small piece of descending pipe gasket make it down and clog that much catylytic space ( those are small gaskets)?
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Sunday, November 15th, 2020 AT 9:18 AM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
I don't think so but check your vacuum at intake if 15" or belwo suspect a clogged pipe. Or if vacuum low at idle like that disconnect the exaust also. But scan for codes and check fuel pressure as well to see what the code is.
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Sunday, November 15th, 2020 AT 9:18 AM (Merged)
Tiny
ROAMINGANT
  • MEMBER
  • 5 POSTS
It bogs down and tries to stall going up little hills as well. Only goes smooth downhill or level ground
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Sunday, November 15th, 2020 AT 9:18 AM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Also check your fuel pressure if low replace the pump and filter.
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Sunday, November 15th, 2020 AT 9:18 AM (Merged)
Tiny
ROAMINGANT
  • MEMBER
  • 5 POSTS
Why would my fuel line all of the sudden have problems? It ran fine, loud because of the exhaust manifold leak, but fine, I could get up to 55 mph, with a little slug to it, but no problems. All I did was replace the gasket, now it runs like a real slug, and going up hill is the weird part
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Sunday, November 15th, 2020 AT 9:18 AM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Do the checks see what you get
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Sunday, November 15th, 2020 AT 9:18 AM (Merged)
Tiny
ROAMINGANT
  • MEMBER
  • 5 POSTS
Went to meineke and scanned. Air flow control modulater, on top of air cleaner is what they say. Came back up hill 6 or so miles and ran poorly still.
Stopped at a friends for a half hour and left. 2 miles down he road the check engine light went off and my truck started running fine. I thought I might have loosened the wire when leaning into my truck, I had my neighbor wiggle the wire and still no light. My truck is running well again, if it ain't broke, don't fix it. Well I hate to say it but that isn't way I do things. Is my modulater on its' way out?
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Sunday, November 15th, 2020 AT 9:18 AM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
It could be a bad connection or you just didn't install it right if you took it off and reinstalled the electrical connection. Probably what happened the modulator was cutting your air off to the engine, hence poor running especially going up hill or with a light load.
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Sunday, November 15th, 2020 AT 9:18 AM (Merged)
Tiny
DII
  • MEMBER
  • 12 POSTS
  • 1991 TOYOTA PICKUP
Im having a similar problem with a 1991 22re 2wd pickup just put a starter pressure plate though out clutch flywheel, took it out for a test ride and it ran great but heard a little chatter turned out to be the water pump replaced it and a fan belt, fired it up ran almost a minute the check engine light came on and it just slowly lost power and died but started right back up and did the same thing. When I moved things to change water pump I unscrewed the plug for what I'm thinking was the mass air flow sensor, didn't damage anything when I realized that wasn't the way, I screwed it back down removed the clip and pulled the plug. And I'm thinking thats where I might have a problem. So this morn I unscrewed it again and seal it to make it air tight again started it up and the light stayed on but it ran for a good 3 or 4 minutes and slowly died off. Its got me stumped. And I can't get it to give up any codes. I did notice I've got an excessive amount water coming from my tail pipe. Anyone have any ideas? Stuck in Ga. Headed too Ar.
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Sunday, November 15th, 2020 AT 9:18 AM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Get the code read so you know what is screwed up and where to go instead of just hit an dmisss.
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Sunday, November 15th, 2020 AT 9:18 AM (Merged)
Tiny
KHLOW2008
  • MECHANIC
  • 41,815 POSTS
https://www.2carpros.com/articles/toyota-trouble-code-definitions-and-code-gathering-method-1990-1995

Above link shows how to go about getting the trouble codes.
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Sunday, November 15th, 2020 AT 9:18 AM (Merged)
Tiny
DEVIOUSLYONE
  • MEMBER
  • 4 POSTS
  • 1991 TOYOTA PICKUP
  • 4 CYL
  • 2WD
  • MANUAL
  • 203,000 MILES
I have a check engine light on, so I checked the codes and I got a 24 and a 27. One is the sub oxygen sensor and the other is the intake air temp sensor. Where can I locate these and fix the problems?
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Sunday, November 15th, 2020 AT 9:19 AM (Merged)

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