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1995 Isuzu Rodeo Repair Question


Topics covered: Mechanic, Engine, Check engine light.
Mileage: 175,000 miles.

Asked on July 25, 2011

Check engine light at some speed/gear combinations

Dear 2 Car Pros:
Mi 1995.5 Isuzu: 2 wheel drive, 4 cil., 2.6 lts. 180,000 miles keeps showing "check engine light" whenever I am riding at 30 to 40 mph in 3rd gear, 40 to 50 mph in 4th gear and 50 to 60 mph in 5th gear. At the same time, it can't pick up speed when this happens.
However, if I lift the foot from the gas pedal the light turns off and when I press it again it works fine for several minutes, until it lights up again if I didn't speed up.
It also turns off if I floor the gas pedal and the engine revs up (with a strange noise) to the upper speed shown above.
My mechanic doesn't find anything wrong with the engine, and since the light doesn't remain on, he can't retrieve any codes.
It only does this (light on and power diminished) within those speeds in those gears, and it's very bothering not to rely in a quick response, as I had for many years.
Please help, this problem have been going on for 3 or 4 months already.
Avatar Asked by Taruno

Answer

Replied on July 25, 2011

You need to get a scan done to extract the fault codes as indicated by the check light, do this first and post the codes here for further assistance.

Tiny Answered by mhpautos (expert)
27,079 answers provided
Replied on July 25, 2011

Who does these scans?
And the light being off (except on those speed/gear situations)doesn't prevent the computer to show any fault codes?
I am an ignorant in the subject, I only know (and trust) one mechanic and he told me he could not read it.
I am trying to find out before having to resort to the dealer, who would cost me half the value of the car.

Tiny Response from Taruno
2 questions asked
Replied on July 25, 2011

many larger parts stores do scans, but they don't often know exactly what they are doing, this should be done by a qualified mechanic, if your can't he may be able to suggest one he knows to do it.

Tiny Answered by mhpautos (expert)
27,079 answers provided

Replied on July 25, 2011

I am a little disappointed with the answers. That I needed a scan I knew before asking the question, and that a qualified mechanic (Isuzu) will do it I also knew. I asked the question to get an idea of what could be the problem, not to refer me back to the dealer mechanic; which was what I was trying to avoid.
But well, have a dinner with my contribution, anyway.

Tiny Response from Taruno
2 questions asked
Replied on July 25, 2011

You have a check engine light On-its a must to have it scanned for code/s, this is the starting point of diagnosis

You can try testing the throttle and vehicle speed sensors

Tiny Answered by rasmataz
68 questions asked