4100 rev dump

[brainhop]

I recent got my timing belt along with other stuff and as I was leaving the shop I was getting on the highway and while getting on it the car nose dived and almost threw me through the windshield.

I had my shop take a look at it to see what happened and they say that the car is designed to cut power when the car is cold at 4100 rpm to protect the motor. He said it did it twice to him when he did it cold.

I know you shouldnt be revving that high when it is cold I usually baby it but it was a nasty highway situation, anyways my question is, Is this true ? Will the car dump power at or near 4100 rpms if it is cold ?

[Zero10]

Nope, once I made a mis-judgement getting on the highway in my 951 about 1 minute after starting it, it ran right up to 6000RPM no problem at all, and it was mighty chilly that morning.

AFAIK, that is BS.
Sounds to me like loose speed/reference sensor connectors, that or they're broken or corroded or something.

When I broke one of the connectors for my engine speed sensor, once I got around 4500RPM it would get very very jerky, since it vibrated just enough at that speed so that the connector didn't make contact. Eventually it started doing it while I was just driving around, or when I hit bumps, and I replaced it.

[brainhop]

Where is that located ? Could you take a picture so I could look at it ? Is this something they could of done to screw it up or something that just happens ?

[ilikemy944]

I have never heard of that before...

[gorfllub]

Sounds like the dreaded "overboost" problem...... Cracked hoses, bad Cyvling Valve, Bad Wastegate, Bad DME. A couple of us have had this problem recently. In both cases: DME.

But, with your recent work, I wonder if they forgot a vac line??

[brainhop]

they took everything back apart and put it back together it seems smoother, I really hate to test to see if it is still doing it because of the rather high rev when its cold.

Could the Lindsey Boost Enhancer cause the problem ?

If it was a one of the items you mentioned would it only do it when it is cold ? I would imagine if it was a vac line it would do this when warm also ? Is there other options I can remove from "possibles" because of the cold/warm variable ?

I would appreciate you helping me nail it down.

[gorfllub]

Yes, I agree...... Vac lines and such should be all the time......

I am not familiar with the enhancer, so no comment there....

Temp related problems can be electronics..... Bad solder joint possibly. Check the connectors at the AFM as well.

I know this problem drove me absolutely nuts. If you know someone near by, try swapping DMEs

[carsonmx114]

gorfllub and i can relate to your problem. your problem sounds a little different, you didn't say if your car did this before your last service or not. if this just started after the service then you should look for a loose hose that would cause a vacuum leak between the airflow meter and the turbo, or a presure leak after the turbo. also you should invest in a good aftermarket boost gauge so you will know for sure what your turbo is doing. since the car doesn't do this after it's warm (warm engines need less fuel) i would guess it's lean so be very carefull, a lean mixture can be death to a turbo engine.

[brainhop]

How can I check if the car is running lean and how can I alter the "lean-ness"

airflow meter and the turbo, or a presure leak after the turbo

you have a picture you can show me exactly where ? whats best way to check to see if there is a leak ??

what boost gauge you recommend ? Isnt the factory one good enough ? how will this help me ?

[carsonmx114]

you could look at your spark plugs and get an idea about your condition, white and chalky means lean and black means rich. chocolate milk color is about what you want. an aftermarket boost gauge will tell you to the exact presure that your turbo is doing. the stock gauge is not very precise, and not as easy to read. it works fine for stock applications but if you going to modify one you should upgrade your gauge. i just bought a vdo gauge for 30 dollars last week. when gorfllub and i were having a similiar problem another member told me about a article on clarks garage that explains how to get trouble codes out of the klr unit, that may help you. did your car do this before you had it serviced? are all three of the hose nipples still on your cycling valve?(round plastic valve under the intake between cyl. 3 and 4) i've heard their bad to break off. also check the hose all the way to the wastegate. it gets really hot behind the engine and this hose does not age well, it can split open and when the cycling valve opens your boost dumps out. let us know what you find.

[nize]

you can get the stock a-pillar replacement, and get an aftermarket airfuel+boost gauge like this;

[carsonmx114]

thats cool nize! that's the same gauge i just got for my car. how does the air/fuel mix work?

[ae1969]

"The car is designed to cut power like that when cold......... " BUHAHAHAHHAHA I wonder where they find these guys....

I wish.

..... Unfortunately you have a gremlin.

Everything listed so far is a possible cause. You just need to be systematic when troubleshooting.

Not fun.

[nize]

alex, you coming up for the seattle north drive tomorrow?

[nize]

carsonmx144;
the a/f gauge connects to the DME and reads the fuel signal from the stock oxygen sensor, then displays it so you can see exactly what's going on.

[carsonmx114]

thanks nize, i think i'll look into getting one. it would be nice to know exactly what's happening as it's happening.

[nize]

http://www.egauges.com/vdo_mult3.asp?Type=Air_Fuel&Series=Sport_Comp&Cart =

[gorfllub]

Nice Pod...... I was thinking something like the HKS CAMP system and doing a screen in the double DIN radio hole..... Of course not as easy to see when driving hard, but I am a techno-gadget-freak

[nize]

i've been contemplating that. the ideal setup would be a pod style gauge for easy viewing, and a datalogging ability. i'm still trying to determine the best solution for this.

[ae1969]

Originally posted by nize
i've been contemplating that. the ideal setup would be a pod style gauge for easy viewing, and a datalogging ability. i'm still trying to determine the best solution for this.

Hehehehe...

Seattle is a little ways from here.

....

That wideband that comes in a self contained unit for a pod is pretty interesting.

It runs ~350......

But to be honest I run my wideband.........tune the car......... and then throw it in the glove box .....never to be seen again.

The only guages I have are Boost, EGT on pod. Oil temp, Fuel Pressure underneath the deck.....

Once you start modifying your turbo......a wideband is a great investment.

Those narrowband ones are ok for a stock turbo..... but really don't tell you much.