Steve 935

Will a RUF chip turn on the check engine light?

BaysideC4

Yes, it did on mine.

DaveK

My chip is not RUF - but each time the Hammer is used on my car it reports a DME failure. Apparently, this is a common problem with after-market chips, so that's probably why your check engine light is on.

BaysideC4

And the most probable cause of why Dave’s check engine light doesn’t come on is because the "check engine light" was not installed on 1990 964's.

So basically, what you are experiencing is normal. The computer is detecting a different chip.

Andy Roe

I belive that only US cars had the check engine light!

Lorenfb

All need to install a check engine light, as this provides a good insight into engine
diagnostics.

jimq

I have a 91 and the light doesnt light up turning the key. I was under the impression 91 didnt have one either. Maybe the PO took the bulb out. If it didnt come with one can I just out a bulb in there and it will work?

Adrian

The check engine light system was installed on all model year 1991, US versions only. Build date from May 1st 1990.
Legally it was required for CA only. Many owners I know have disconnected it because it is on and they cannot find anything wrong with their car so they remove the light bulb.
Ciao,
Adrian
964C4
GT-2

PS: Model year 1991 for the USA started on 1st May 1990 for the 964 production line.

jimq

Thanks Adrian. Probably shuold have check the "book" before asking. i will get a bulb and see what happens.

BaysideC4

I installed the bulb in my 1990 C4 and it worked. No problems until I installed the RUF chip. I ended up taking the bulb out again.

Steve 935

My 1990 (Built Jan 1990) had no bulb in the socket. Not sure if someone took it out.I put in the bulb and it lights up with the ignition on and then goes out after the car is started(normal operation).I wonder if it came from the factory with a bulb or not.

BaysideC4

It came without the bulb, adding a bulb seems to work in some 1990 964's.

Adrian

1989 models came without bulb and wiring.
1990 models came with wiring but without bulb.
1991 models came with wiring and bulb.
Whether it works or not properly depends on the part number DME installed.
All is explained in the book.
Many tests have been carried out and sometimes it works and sometimes it doesn't and if you install an original original RUF chip or a copy made in the USA you will get fault code 1142 and a check engine light if fitted and the only way to get the light out is to remove the bulb.
This problem was solved with later versions but you have to purchase the whole DME, I think. I am not sure if these chips were sold onto the tuning market as separate items.
Ciao,
Adrian
964C4
GT-2

Steve 935

So I guess anyone with a chip will have a check engine light come on.Didn't know that.

You guys that have a aftermarket chip. What are your thoughts on the improvement?I would like my car to rev quicker through the rpm range in second gear and up.

DaveK

My thoughts on mine are - when I get around to it I'll go back to stock. When I got it I thought there might be a slight difference - but when I went back to a stock DME briefly it felt just the same. I didn't get the original chip back - and I would want the oxygen sensor refitted - so I can't do it myself.

At least in my opinion - I now have a car that requires super unleaded all the time, with no noticeable power gain.