[Mk2] [Turbo] Idle & Engine management light issues

[Pauln]

Ok, I've been having idling problems with my turbo. ie seems to go up and down like a yoyo, but on the move the car runs fine and no error codes and engine management warning light goes out as soon as I start the car.

I've gone through everything else so I'm pretty sure it's most likely a sticking idle control valve, so I'm in the process of acquiring another complete s/h throttle body that I can thoroughly clean up, check and setup and then simply get them swapped over so I can keep the car running in the meantime.

But today the engine management warning light came on as I drove away, then started flickering and getting dimmer. By the time I'd gone around the block and returned home it had gone out again.

But now every time I start the car the warning light stays on for a couple of minutes and then slowly fades out. I checked for error codes and there are none.

Is it just the idle control valve issue again, or is this likely to be a different fault that has developed.

Grateful for any suggestions.

Paul

[markstevieandmads]

Id put my money on blown or leaking capacitors in the main ecu or the air flow meter.

Pop the lid off and have a look at the ecu for a quick and easy check.

The only way to check the afm is really to replace it. I had a problem with my eng management light to lighting. Found leaking capacitors and a dodgy afm.

Very common problem.

[Pauln]

Thanks for the suggestion, I'll whip the ecu out tomorrow and take a look. The car was in the body shop for around 7 - 8 months, and having Googled leaking caps in the ecue, I've seen it suggested that long lay-offs don't help, so you could well be right.

Paul

[Pauln]

Took the ECU off this afternoon to have a look, and I think you're probably right. There's a couple of 50v 10mF caps in there that don't look at all healthy. Bummer. I've only just replaced the ECU on the NA, now it looks like the Turbo has come out in sympathy

Unfortunately one of the hard lessons I've learned is that rev 2 parts like this seem to be much harder to find than rev3 plus. Presumably partly due to the short life of the model, but at least the same ECU seems to have been used in other Toyota models of the same vintage.

Paul

[markstevieandmads]

I have a spare for rev 2 turbo. I bought a secondhand one that ran fine while I had my old one repaired. I then put my repaired one back on and the spare is in the garage.
Feel free to pm me.

[bigal]

Failing that you can get the ecu repaired like I did, cost me 40quid.

[Pauln]

Out of interest who repaired your ECU for you?

I was thinking of having a go at repairing my old one myself as a spare as these seem to be getting hard to find, but wasn't looking forward to the job.

Paul

[Pauln]

I've now fitted a replacement ECU which has cured the engine management light issue, but sadly didn't cure the idle speed issue.

I also recently acquired a replacement rev 2 throttle body which I've given a good clean, checked the TPS and ISCV resistances were within spec, and checked the ISCV fully opened and closed when applying 12v to the relevant terminals.

So today I replaced the existing throttle body, which was pretty grubby



with the one I'd cleaned up and checked





using new gaskets and a new length of SFS hose for the air intake line. I also checked that +12v was arriving at the middle terminal of the ICSV when fitted to the car.

Unfortunately the idle speed when fully warmed up is still around 1100 rpm according to the tach. This initially rises when you switch on the aircon (as it should) but then sometimes starts to drop back to the original level, even though you can still hear the AC compressor running.

When you switch off the aircon, the idle speed drops back a little and then starts creeping up to around 1100 rpm again.

I'm starting to wonder if there's an issue with the aircon idle up valve and was going to see if it needed adjusting, but unfortunately found the adjuster is "rounded" so suspect someone has been playing with this at some point.

So I'm now on the lookout for a replacement ac idle up valve for a rev 2 part no 90910-13003.

What's really annoying is that the na I sold last weekend had a rock steady 800rpm idle speed.

Paul

[danjama]

Sounds like I have similar issues to you. My old Rev 2 turbo had a rock steady idle at all times. My current rev 2 turbo sounds very similar to yours. I'll have to check my ECU and maybe try to source another AFM to test.

I did replace my coolant temp sensor and that improved things a bit, have you tried that? Worth a go at £15.

[Pauln]

As I wasn't making any progress I decided to clean up my old throttle body and check everything over. All resistances were within spec, applying 12 v opened and closed the ISCV. So I then tried adjusting the ISCV to make sure it was fully closing. Having checked and setup the TPS, I then swapped the throttle bodies back as I had at least seen a 800 rpm idle at one point with the original throttle body.

Unfortunately this made absolutely no difference and she still idles around 1,100rpm when warm.

Whilst the throttle body was off I noticed another vac line underneath the body that I hadn't changed, so I replaced that just in case the old one was leaking. I also found a couple of valve cover bolts were loose so tightened them.

Today I unplugged the MAF connector and checked that the resistances were within spec, and rechecked the "idle screw". I also tried the dodge suggested in these forums of starting the engine multiple times, and removing the EFI fuse for 10 mins.

But she still refuses to idle at anything below 1100 rpm as indicated on the tach. Mind you I do wonder how accurate that is as I've noticed when you turn the ignition on without starting the engine the needle goes up slightly I'd guess around 100 revs or so. It's a replacement gauge, so perhaps the previous owner took the needle of when he fitted Speedhut dials.

So, as you say, for £15 perhaps it might be worth changing the EFI temperature sensor. It's definitely worth checking your ECU to see if the capacitors are leaking as these can then damage the tracks and cause no end of issues.

Any way I'll give her a run in the week to blow out the cobwebs and check everything else is working OK.

Paul

[thomp1983]

If you can hang on a week paul i can send you my obd dongle and it will show you the exact rpm and temp and some other bits, im just waiting on it returning from the states

[Pauln]

That would be brill.

Be good to know to know the real values I'm dealing with. Ill drop you a PM.

Thanks
Paul