944hal

Looking for a stock Turbo S KLR chip. Anyone have one they've replaced and like to sell?
944hal

Rogue_Ant

Really not much of any difference in KLR chips... one from about any year will work.

944hal

Didn't know that. I thought the KLR controlled max boost RPM level. Around 5,500 for the regular turbo. Extended it beyond that RPM.

Rogue_Ant

If you are running the stock CV, then yes, the KLR does control boost and boost response. But there really isn't much difference between the years... The Turbo S had the larger K26/8 that was able to hold boost easier than the K26/6, which is the only real power difference between the Turbo and Turbo S.

944hal

I'm running the stock CV and turbo. Everything pretty much stock except 3" exhaust, no cat and flow through muffler. Using a performance DME. Was having overboost limp home mode problems after I installed the more open exhaust. DME chip fixed it. Dedicated track toy. Thanks for the info.

Rogue_Ant

No problem

Oddjob

Do you have a separate boost gage showing how much boost the car is making? Make sure you dont have a real overboost condition, like a sticking or damaged waste gate. An aftermarket open exhaust should not increase boost enough to trigger overboost protection on a Turbo S.

944hal

I'll pass along the following comment that I found on a 944 cup forum about rules changes. It described my situation exactly.

"One of the problems with running a stock DME chip is that if you open up the exhaust (larger pipes, low restriction muffler, cat delete, etc) is that the DME will go into overboost protection mode by cutting out the injectors with any sustained boost over 5 psi once it has been triggered. Only way to reset is to shut off the car and restart. The limit can be easily rasied and reprogrammed by burning a new DME chip but it will no longer be considered stock, even it it has the same maps"

I don't know enough about the programming to explain why this happens.

_________________

Oddjob

My point is that just opening up the exhaust will seldom increase boost enough to trigger overboost protection, especially on a Turbo S (as the overboost protection setpoint is less conservative on an S, than a k26/6 car).

You want to make sure you do not have some other issues that are creating an overboost condition.

How much boost is the car making?

944hal

Your point is well taken. My car is not an S, it's a pretty much stock '87 turbo. Sorry I didn't make that clear. Because of the problem above it will not run with a stock DME. I was racing the car PCA Stock-E but a performance DME chip is not legal. Therefore, I'm moving it to SP3. I was assuming that a Tubo S KLR chip would allow the boost to stay on past 5,500 RPM, even with a K26/6. True or not? That was the reason I was looking for the chip. The car was in the shop and was tested for overboost. It was not overboosting. I don't currently have a boost gauge beyond the stock one. But even it was not showing overboost. I struggled much of last year with the problem. It was suggested and we tried the other DME and it worked. The reference I copied was the first indication I'd seen that opening up the exhaust could cause the car to go into limp home mode due to overboost. Sorry for the wordy reply. I hope I made my issue a little clearer. Just getting into this forum stuff. A world of information out there.

Oddjob

Sorry, I assumed that since you were looking for an S chip, that you had a K26/8 S car.

"Limp Home Mode" and overboost protection are two separate and independent functions. The limp mode is a safety response (lower boost, retarded timing) to a diagnostic fault detection peformed by the KLR. The overboost protection is a hard fuel cut off by the DME, when airflow through the AFM exceeds a preset limit. The limit is mapped on the DME chip. So if you want to increase or eliminate the overboost protection, you need to swap out the DME chip, not the KLR.

Typically, the overboost will most often kick in above 5k rpm in 4th gear. May trip it occasionally in 3rd, but unless the car is making huge boost it usually requires full pulls well into 4th to stumble.

The stock K26/6 DME chip is more sensitive to overboost, but there is still reason to be skeptical that deleting the cat is enough to trip the fuel cut.

Do you still have the stock WG, or are you running a lindsey clubgate? No shims in the WG or jet in the banjo bolt?

Any leak in the boost control line or small tear in the WG diaphragm, or WG valve sticking will be enough to increase boost.

If the car is running actual stock boost (around 10.5 psi at 4k, somewhere down around 8 psi above 5.5k), a faulty DME or AFM would also be a possible cause of a pre-mature overboost cut.

How did the shop check for overboost? Did they hook up an aftermarket gage?

944hal

I installed a performance DME chip and raced the car earlier this month. No problems with overboost. Car ran very well with the new chip, although a little rich. Boost, (according to the stock gauge) was normal. I'm running a Lindsey wastegate, only a few years old, no shims or messing with the bango bolt. No leaks in the system that I can detect at this point.

Basically, swapping out the DME chip fixed the problem. So, I'm back to my original question, which is, with a different DME chip, will installing a Turbo S KLR prolong or increase the boost on a 26/6 car?

Oh, good point on Limp Home vs Overboost. I'm pretty sure it was overboost related to the DME since a new chip fixed it.

Hal
'87 951
'89 S2

Rogue_Ant

Are you limited to stock equipment?

944hal

The way I read the rules an aftermarket DME chip is allowed. KLR is suppose to be stock. Cannot change the boost beyond factory level. I'm temporarily keeping the 26/6 but trying to eventually take the car to a 951 S from a stock 951. The K26/6 will get replaced with a K26/8 at some point but if I can get some gain from the S KLR chip I'll go for it. If not, the stock KLR will have to do.

Rogue_Ant

The S KLR chip will try to build boost a little bit earlier, but max boost is pretty much the same as the non-S.