Engine Trouble

[Gavin]

I've got a UK spec MR2 Mk2 1992

On start-up car idles correctly, but then starts to fluctuate between 800 - 1100 rpm. If I'm in a low gear say 3rd, and at about 2000 rpm and I accelerate lightly the engine is smooth and accelerates normally. If I however accelerate more rapidly the engine badly misses to the point where it almost stops. At this point if I dip the clutch, stop accelerating the engine returns to idle with no problems.

If I try the same again, but starting at around 3500/4000 rpm the car accelerates correctly both ways, (lightly and more rapidly) and does not miss fire. I don't think it's a fuel starvation problem as it works OK at higher rpm.

Any ideas?

P.s. I've replaced the following to try and eliminate things

HT leads

Rotor arm

Distributor cap

Spark plugs

[longhallage]

1) May be a vacuum pipe. See family post "Idle Revs"

2) Possible fuel line/injector issue.

3) Make sure your timing is not out - as you've changed the rotor.

4) If you have touched the distributor you need to make sure the centrifugal governor is not sticking as this could cause irregular idle and poor advance.

5) you may have a blocked 'pick-up' throttle bypass - unlikely but you never know.

Not 100% sure

Nick

[Gavin]

Thanks for some pointers.....

You mentioned that the centrifugal governor might be sticking as this could cause irregular idle and poor advance. Am I right in thinking that this is inside the distributor, and is not easily accessible, or can I see this by visual inspection when I take the Distributor cap off?. Also is there anyway I could check that it is sticking, or is it a simple replace and hope.???

Thanks

Gavin

[longhallage]

the CG consists of weights which, accelerated, change the timing (advance). they are located under the contact breaker base plate and aren't that accessable. I'm not sure this is really the problem. i feel it is more likely to be an issue of vacuum integrity but i can't quite put my finger on it.

Try asking unity jon, he seems to know these sorts of things. SuperchargedIS200 is an engineer. he will know.

Sorry, nick

[Gavin]

I've bitten the bullet, and booked it into Toyota.

The've had a look at it, and said that it was the spark plugs that were the problem!!!

Hmmm...Not sure I'm buying that. I put a new set in at the weekend, and adjusted the gap as directed by the Manual.

I must admit that the gap did seem a little large (book mentions 1.1mm). Have I misread this?

Does anyone know what the gap should be. My engine is a 3SGE.

I have to admit I don't think that this is the problem, as the car was missing before I changed them.

[longhallage]

That does seem quite large but if that's what the manual says....

Don't take any **** from the garage though :censor:

Nick

[Gavin]

Have to say, I've got to eat humble pie.....

They did apparently only change the Plugs, and it seems to have cured the problem.

I'm still confused to why a slightly large gap would make such a difference, but it starts on the button, and has no miss under acceleration.

The manual definitely mentions 1.1mm for Plug gap, but I'm not sure whether it was referring to my engine or not as the manual mentions 3SGE and 3SFE engines.

The only thing I can think of, is that with a weak spark, there would have been unburnt fuel, and maybe there's a sensor that picked up on this and tried altering the mixture causing it to miss. Not sure but I'm a very happy MR2 driver again...!!

Have to say garage was very good. Bromely Toyota. Will definitely be going back there again for future work.

Total for plug changes including labour £52.... Bargain..!

Thanks for all your help longhallage.

Gavin

[TheNissanMan]

post a review in the dealers revies section :)

that's the sort of feedback we need...