Randy Carter

At the end of this post I'll list what we've done recently as we've had several problems lately.

Once we got the car running well, we noticed the CHECK ENGINE light coming on when we let off the throttle. As soon as we gave it gas the CHECK ENGINE light would go out. I was advised that as the car was running so good ( and it was ) that I should disregard the CHECK ENGINE light.

We ran it maybe 100 miles or less in that condition but this weekend we took the car to San Antonio. Within 20 miles the CHECK ENGINE light came on steady and would not go out.

The car (highway speed surged perhaps a little but had full power otherwise). When we pulled off to the side of the road the engine stalled. Had to start it in neutral and give extra gas to keep it running while shifting to drive. We got home okay but if I try to start the car it dies. I have to start it in neutral with extra gas to keep the revs up or it dies. If I keep the revs up, I can slip it into drive and get moving. Once at speed, it has full power and operates fine except for a little surging/roughness to the engine.

We previously had somewhat similar problems and found the fuel pumps clogged (both replaced) and the maf blowing out of it's boot.

The maf is firmly secured and does not appear to be related to the current problem.

Suggestions?

Thanks in advance for your comments.

Randy & Cheryl

DR

Randy,

First check the codes to see why the Check Engine Light is on and let us know what you find..

Shop manuals > Volume 1-A > Section 24 > Page 29 for info on checking and deciphering the Check Engine light flash codes.

Jim M.

Randy,

The check engine light is tied to emmissions equipment more than anything else. I'd start by having it checked with the hammer. Short of that you can check it with the on-board diagnostics, but you need the manuals to figure out how to do it.
When the fuel pumps were changed were they contaminated with crud? Did they flush out the 17 years of accumulated garbage from the tank. What I'm asking is; could the pumps be contaminated again???
Typically the problem you describe would lead me to think the idle stabilizer is part of the problem. But, because of the SC and all the associated mods, all bets are off.

Randy Carter

Thank you, Dave & Jim. Unfortunatley, the only hammer I know of in my area is for driving nails. Whatever the case, we've been planting all day and I am going to bed. I doubt I could type a coherrent sentence to save my life; I am that tired.

The obvious question is; if I insure & pay for the shipment, is there any way I can have a hammer shipped to me for a day or two?

Thanks again, guys. Seriously, I am off to bed.

Tomorrow....

DR

I'm sure everyone would that HAS one :-) But I am sure everyone has a gas pedal and an ignition key close by.

The light comes on for a reason, and the light will tell you that reason. It may not be THE reason, but it will start you on the right path....and you don't have to wait to buy, beg, borrow, drive to and/or pay someomne that has a hammer.

With a simple Engine check flash code test, just maybe we can help further, which I can only assume why someone would post here for help???

Randy,

If you continue to have the problem with the hose blowing off the MAF, I have a proven solution that will guarantee it will never happen again.

Also if you don't have the shop manuals or a PDF version I can post the pages of how to test it for you, it is very simple and would take less time that it took to type this reply (easier too :-).

John Speake

The most likely thing is that the check light is telling you the O2 loop is out of range.

This could be due to a number of reasons, but you should be able to pull the flashing codes from your digi-dash, as per Vol 1 A of the WSM, right at the back of the volume, page D 24/28-29.

My Euro version of the WSM does have the code explanations that are supposed to be on page D 24/28/7. However all the LH codes are shown in Appendix 1 of the "Spanner" User manual avaialable from my website here....

http://www.jdsporsche.com/faqs/DIAGN...20ver%207a.pdf

ROG100

Randy,
Happy to send you the hammer if you do not want to access the codes your self.
Once you hook it up I can talk you through the proceedure.
Reading the codes from the dash may be the only way to go as the chips you have in the car may stop us from using the hammer.
Call me I am in the office.
Roger

AO

I have found that the "Flash code" no longer works with the non-stock chips, so you might not be able to get the codes this way. For others following along wondering what the "flash code" is, it's when you turn the ignition to ON (don't start the car) and mash the accelerator and hold it for 5-10 seconds. The check engine light should flash you the code. This is only on 90+ cars (I'm pretty sure 89's didn't have this even though they had the digital dash).

Throwing in my $0.02, the stalling could be a bad TPS, but that doesn't explain the surging. A bad MAF might explain both.

DR

True, when the MAF inlet hose popped off all it would take would be small debris to hit the wire and cause issues.

Randy,

If you have a spare MAF try swapping it out and see what happens.

BTW, some "non-stock" chips don't work with the Hammer too, so if you can't do the Flash Code test, I wouldn't waste too much effort getting a Hammer sent out, at least until you can confirm what non-stock chips you have, if any.

If you have SharkTuned chips (or better yet PEMs) you will be better off borrowing an ST2 than a Hammer. I can get tons more diagnostic info from the real time sensor data and on road data logging with the ST than from just reading error codes on a Bosch Hammer.

Keep us posted and good luck!

Randy Carter

Originally posted by DR
Wow! I'd never even heard of this. Yes, I'll definitely figure out how to check the codes. Hell, even I can do that... no wrench required.

Thanks for all the suggestions everybody. Yes, we have a second '93 GTS so I could try swapping the MAF if it comes to that.

I'll keep y'all posted as I pursue the root cause.

Thanks again.

John Speake

It would be good to know what the spec is of the car..... in terms of chips etc.

ROG100

Hammer does not work and flash codes do not work (Andrew good call).
Disconnecting the MAF first to see if anything changes.
Then swapping the MAF from the other GTS.
Back with the results.

John,
Car has a Murph/928 MS type setup. Engine was rebuilt by Devek.
Others on here - Bill Ball - know more about the car than Randy and me.
Chips are not PEMS as far as we know.

We could use the ST on the car but it would need us to be there to do it.
Maybe another road trip.

John Speake

Thanks Roger. If it is a Stage 3 Murf, it will have Sharktuned Mk 1 chips, it may or may not have PEMs.

Murf Stage 1 & 2 used an FMU with stock chips.

Mk 1 Sharktuned chips will not have the flashing code feature. A special version we made will work with a Hammer.

Sharktuner Mk2 chips will work with Hammer, they do not have flashing codes.

ROG100

https://rennlist.com/forums/928-foru...-for-sale.html

Above is the link to the info on the car.

DR

According to For Sale ad...

"Vortech T-Trim supercharger running at 5.5 psi"

Probably a Stage 1, not 2 or 3 (Murf , you around??)

Could still have stock chips, do the Flash Code test and see what happens, that could confirm stock chips...or not (and save a lot of time).