[ether_joe]

okay, so I am still trying to put the fix on my 6000-rpm cutoff issue.



to recap, after 6 minutes of normal 6800-rpm cutoff the car begins cutting off at 6000 rpm. This is the same behavior Dave G. helped located in the manual - manual says it's due to a fault in the ECU. (*sniff* . . . come back Dave. . .)



I have done the following (most of which needed to be done anyways on my 80K car)

new o2 sensor

new plugs (bosch copper)

tank of 100 octane

disconnect the battery for 10 mins

blink test (shows 1-5 'no fault')



next step is to examine the ECU as many have recommended. Get the part number, confirm it's a stock chip. Some local 968ers have also offered to do an ECU swap to try and isolate teh problem.



I am wondering though -



Why don't I just put in a perf chip and see if that shakes the demon loose. I mean, i'm going to chip the car anyways. If it doesn't work then I've only lost time. If it works I've fixed the problem and done the chip also.



I know it's not strict troubleshooting but honestly if it fixes the problem, I don't care.



thoughts?

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[flash]

i don't see how it could hurt anything - you can run the car with the DME half hanging out, so if it doesn't fix it, you're already apart and can deal with the DME - if it fixes it, then just button it up and count yourself lucky



do yourself a favor though, before yanking and replacing the DME, and get some contact cleaner and give the contacts of the DME a shot - never know

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[flash]

addendum to above comment - check the rev thing with no load, not driving - if the perf chip was on the lean side, and then you loaded it up with a problem, you could do some damage



you should be fine though just sitting in the garage

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[ether_joe]

you know now that you mention it, I don't think I get the issue when the engine's not under load. I'll have to check that tonight.

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[flash]

if you don't, then it's probably not the DME

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[ether_joe]

I will check more carefully.



I'm realizing that usually when I'm revving high without load, it's cause I'm blipping the throttle to listen to the engine. <img src="/forum/images/smilies/968/smile.gif" class="smilie" alt="" /> I need to do the load test more scientifically, I'll check it tonight.

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[ether_joe]

okay tonight I was scientific about it against the clock.



- cutoff does happen when the car is out of gear (just harder to notice as I'm not getting jerked around, but it's burbling right there at 6K)

- cutoff is definitely happening at 6 minutes. Not 5, I used my cellphone clock, started at 6:48pm, at 6:53 it was smooth and at 6:54 it started wanking out on me.



may be able to open up the ecu tomorrow and see what Iv'e got.

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[josephsc]

Sean, I'm headed back up North on Saturday and leaving on Wed -- I've got a few things on my todo list, but there might be time to do a quick little DME swap. Give me a call later this weekend.

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[ether_joe]

cool thanks. <img src="/forum/images/smilies/968/smile.gif" class="smilie" alt="" />

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[ether_joe]

well, thanks to a bunch of help from Mr. joesephsc, swapping brains with a loaner he provided DID fix the problem.



And hey-ho, the Porsche Gods also blessed us with an opportunity to fix the heater control valve while we were at it. . . you can imagine from there <img src="/forum/images/smilies/968/ohmy.gif" class="smilie" alt="" />



So. . . . either fix the current brain or get a replacement. . . but here's the good part - Joe's loaner brain has a Promax chip! whoooooah! What a difference! (Part of it is just being about to push the car beyond 6K. . . but I really do think i feel a difference, even a bit down low.) whoa baby! new brain, perf chip, and airbox mod - I can't wait!!



anyhow thanks to everybody, I now have a solution and a plan, now it's just a matter of time and money.

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[odb812]

sean, i'm sure someone else has an answer to this, but you should be wary of your dme part number. the last two letters of the part number for the dme indicate which of the 3 dme's are in your car. .00 was produced until sept 91, .01 until december 91, and .02 from then on. the rsbarn, promax, speed-6 chips all work with this last dme. if you have the .01, i believe weltmeister and/or autothority may make a chip for this dme. if i remember correctly flash gave me some good info on this when he was doing his chip test. these are just some things you should keep in mind. also, if anyone reads this, would there be any problem with putting a .02 dme in a car which came with a .01 dme from the factory?

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[ether_joe]

[quote name='odb812' date='Apr 23 2006, 10:38 PM']sean, i'm sure someone else has an answer to this, but you should be wary of your dme part number.  the last two letters of the part number for the dme indicate which of the 3 dme's are in your car.  .00 was produced until sept 91, .01 until december 91, and .02 from then on.  the rsbarn, promax, speed-6 chips all work with this last dme.  if you have the .01, i believe weltmeister and/or autothority may make a chip for this dme.  if i remember correctly flash gave me some good info on this when he was doing his chip test.  these are just some things you should keep in mind.  also, if anyone reads this, would there be any problem with putting a .02 dme in a car which came with a .01 dme from the factory?[/quote]



Todd thanks for the reminder, yep I remember the thread and will check it out. I have a pretty early 92 car so I wouldn't be surprised if I have the early DME.



I was going to take it out when I was working on the car Saturday, but I got interrupted by trying to take the @#$@# fill plug off the tranny, bending the allen wrench in the process. I didn't have the energy left to take the frame out.



so



I will probably take another swing at this Saturday. . . will have the dme part numbers for you guys then.



thanks

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[flash]

the ECU number that would give you grief is 0261.200.474



most people have 0261.203.070



there is no "00" or "01"



there were 3 combinations, but only 2 DMEs



the first one was only in the very first few cars, and i have yet to see one, and have only heard of perhaps 2, but even those are unconfirmed - we've gone back to about the 20th car so far, and still are showing the later ECU - it may well be that all US cars had the later ECU



according to development work done by the older companies, it is true that the early ECU does not work well with aftermarket chips other than autothority and weltmeister specifically for that ECU - i don't know how they figured that out without having one, so i guess somebody got their hands on one - i don't know exactly what the problem is, but since nobody has yet turned out to have one, it seems moot

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