Unichip Issues? Random engine check light.

[RXWPN]

Hi Guys,

Its time to ask the experts im really stuck now....

Ive been having problems for nearly a year now after I had a Unichip piggyback ecu installed on my 97 Legnum VR4. Have since the second day driving it had an engine check light appear when just cruising on the highway/motorway with very little throttle. Car goes into limp mode and sounds terrible, then I restart it and its fine.

Mitsubishi in Wellington diagnosed the ECU and found a TPS fault so I had them install a new one and calibrate it etc, but engine check light still appears and the ECU isnt storing a fault. On a 50km journey can happen 5 or 6 times and appears to be getting worse.

It seems too much of a coincidence it happened the day after the Unichip installl however the installer says it definately isnt that, and has since shut down and moved on so no help from him.

Has anyone else got a Unichip installed or anyone able to shed any light on this issue its driving me crazy!!!!!

Other mods of not are: 3 inch exhaust, large K&N filter, intercooler etc. Eboost controller set to 14psi boost most of the way through the rev range.

Thanks for your help...

[Turbo_Steve]

Well the first thing we need is for you to read the error codes off the ECU, which will tell you WHY it's entering an error condition.

This can be performed with nothing more expensive than a paperclip: there is an article in the members section, but basically you short two pins on the diag port and it will flash the check engine light a number of times. You count thelong flashes, then the short flashes, which tells you what the error code is.

This will pretty much tell you why the ECU is upset.
I suspect there is a sensor going "out of range". Or that there is a signal being interrupted.

[psbarham]

yup hairdryer Steve's on the money, get the fault codes, I would bet its something to do with a bad joint where matey has spliced into the ecu loom

[Nick Mann]

I used to have a unichip and another member did also.

Neither of us had that issue.

[RXWPN]

Hmm, Yesterday at Mistsubishi they said there were no codes stored so it cant be a hard fault. Im just worried it was wired up incorrectly. It seemed that the TPS was the reason but a new one didnt fix it and its getting worse.

Does the engine check light have to be on when you do this error code check?

Ill join as a member tonight anyway so ill check the article.

Cheers

[Subaru ETA]

logic dictates that the guy who did the unichip has bulls it up. im thinking dodgy connection at the ecu which is a feed from the tps - hence the thinking that it was the tps that was at fault

[Turbo_Steve]

I can't believe it's going into "limp" mode and not recording ANY error codes?

[elnevio]

I can't believe it's going into "limp" mode and not recording ANY error codes?
:iagree:

Even if the error has gone away, the code should still be stored until it is wiped.

[RXWPN]

Yea so i would have thought but it has stored nothing I cant understand it. Mitsubishi have asked ne to brin g it in with the fault showing.

I have spoken to the guy who did it finally and he has supplied me with a Bypass cable that allows you to use the standard ECU so I can eliminate the Unichip as a fault. He thinks it might be a an issue with the tune at that level of throttle so this will tell I suppose. Didnt show on the dyno though but will wait and see.

Thanks for all your help guys really appreciate it! :P

[Ryan]

Hope it all comes out in the wash for you mate :thumbsup:

[Turbo_Steve]

Or could it just have a short to the CEL bulb? :)

[RXWPN]

It wouldnt go into limp mode though if it was just a short in the bulb would it?

[Turbo_Steve]

Depends what it's shorting to.....if it's the RPM inputs or the MAF then it might behave very oddly. I agree it seems unlikely, though.

[AlanDITD]

Have you actually tried pulling the codes yourself?

Its the easiest thing in the world, and considering most garages/dealers out there are sh1t, i would want to check anyway.