[Mk2] [NA] G-limited won't rev past 5k rpm

[Welshowz]

As the title basically noticed the car was down on power towards the end of last week changed plugs leads and dizzy cap still no joy. Car will rev fine up to around 4-4.5k rpm at which point it struggles to carry on climbing through the rev range as it used to. Seems to be making a hell of alot more noise from the air filter too. Anyone had any similar problems? Not really sure which direction to head next to be honest!

[Nic]

I'd start by checking the ECU for fault codes. Open the grey diagnostic cap in the engine bay, then use a stretched out paperclip, push one end of it in the E1 hole, the other in the TE1 hole. Turn the ignition on (without starting the car) and watch the red engine warning light on the dash.

If the warning light flashes continuously there are no stored fault codes.

If there is an error code stored, it will flash a number of times, stop, then flash another number of times, count the sequence of flashes, eg. if it flashes 5 times, stops, then flashes 2 times the error code is 52 - Knock Sensor Signal.

Do that, then look up the error code you get here:

http://www.mr2oc.co.uk/know-your-2-know ... bartid=162

If you do get an error code post up what it is.

[Welshowz]

Completely forgot to mention I'd done diagnostics too no faults stored

[Welshowz]

Will also rev to redline in neutral but not under load. Possible the timing belt has jumped a tooth maybe??

[MartinF]

Yeah, sounds like it could be an ignition or cam timing issue. Both relatively easy to check.

[Grazzy]

This may be worth a quick check, im not saying its the problem, I had these issues a couple of months ago, turned out a replacement ecu had 2 blown caps in causing this problem. its only 4 screws on the ecu top plate to check.

[Welshowz]

Well it went away for a couple of weeks was driving fine but it'd shown it's face again this weekend coming onto a slip road put my foot down in third gear what felt like a miss fire at around 3.5k and it's back to how it was really sluggish and not revving properly again driving me insane now lol
Regarding checking the ecu is it pretty obvious of they're blown?

[Grazzy]

here what mine looked like, one was leaking the other had changed colour and started to bludge


http://postimg.org/image/agpp1zyjb/

[Welshowz]

Awesome cheers mate will have a look when I've got a spare 5 mins this week and report back!

[Grazzy]

no worries, mines started at about 6k, I think the more it leaked the less max RPM's I could get. I think I ended at not be able to get over 5K towards the end.

but I had changed everything on mine. plugs, leads dizzy cap etc. thinking what the hell is causing this problem. no fault codes. Was looking for something about the PFC I had when I stumbled across a post with one with bad caps in it. When I check my stock ECU hey presto, pretty much the same 2.

[Draven]

i had this exact problem with mine a couple of caps on the ECU had melted..

I got a replacement ecu.. problem solved.

[Welshowz]

Ah I hope this is the problem been pulling my hair out with this lol fingers crossed

[Welshowz]

Right just cracked the ecu open doesn't look too bad although someone's been at it before judging by the rounded off screws lol
Few things I noticed the two main caps in the pics have been leaking slightly could this be the problem? Also as it's a rev3 import will I need an ecu from an import??
Not letting me attach pics as I aventurine posted enough apparently lol

[Grazzy]

do you know anyone near you with the same year MR2 to quickly borrow the ecu? that would give you the answer right away.

[Pauln]

It's not so much the caps being faulty that can cause major issues, its that the sludge that leaks out of them can quickly eat into the pcb tracks and thats when you really start to have major problems.

If you've caught it early, it should be possible to just de-solder the old caps, clean up the tracks to remove any sludge, and solder in a couple of new caps. It's not that difficult a job, and you should be able to buy suitable caps from RS components in Cardiff.

Those caps are a common issue, especially as these ECUs get older, so if you do buy another s/h ECU you really should check they are not starting to leak and better still change them any way to avoid future problems.

I had the leaking caps issue on my tubby, but as the tracks were really badly damaged I purchased a s/h ecu to fit. I was told this was working fine, and I've no reason to doubt that, but when I opened the ecu to check the caps you could see that one of the caps was just starting to leak so I changed them both whilst I was at it. Bit of preventive maintenance

Paul

[Welshowz]

Cheers for the replies guys
Nah don't know anyone near by with a ecu I can try I'll look into getting the caps changed or even getting a second ecu to try at least then I have a spare to change the caps on without the car being completely off the road as it's my daily.

Does anyone know if I need the same ecu from a g-limited or can I use one from a UK spec rev 3?

[Welshowz]

Bit of an update. Been searching for a second hand ecu with no joy so far. Finished work at 2 today car is back to normal
Literally pulling my hair out with this haha! Surely it can't be the ecu if it's "fixed itself" ?

[Welshowz]

Right I think I've cracked it and I think it's down to the leak in my boot haha! Seems to come when it's been raining so I've gotta sort this boot leak out to make sure

[abovetherim]

If it mainly misbehaves in wet then I would inspect the coil and ignitor.
The coil pack can crack and let in moisture. Also the bracket is earth for ignitor so clean this up as it will be rusty

See here http://www.imoc.co.uk/forums/viewtopic. ... light=coil

[Welshowz]

Yeah my weet theory is out of the window! Although I'm gonna try a new coil as that was the next thing in my head driving me wild now!