Chris White

This one has an interesting story behind it –
Its an 1988 Turbo S that belongs to the original owner (!). When it was new he had it over in Germany and in the first year of ownership it blew a head gasket (no mods) and the factory did the repair – they found no problem. Since that time it has been through 12 head gaskets (!!!) The Owner is fairly attached to the car so he commissioned a complete new engine with lots of nice options – Stroker, solid cam, bigger turbo, MAF and a lot of other niceties. That made it a couple of hundred miles before the head gasket blew!

After that the Owner contacted me and he was a little exasperated over the whole thing. After lots of discussion and pondering I recommended going to a standalone management system. On this one I used a Haltech unit in order to utilize some extra protections – the ECU is programmed to give a warning and also greatly reduce power if the coolant pressure goes over 15psi (early sign of head gasket failure) Detonation was the problem that kept causing the head gasket failures and everything had been replaced except the base engine management. In addition to the standalone we added in a J&S Safeguard knock control unit just to make sure we had complete control over any knocking. Running in full sequential mode with individual coils we have the ability to control mixture and spark by cylinder and the J&S will retard the timing on just the cylinder that is starting to show any signs of knocking.

After fixing a couple of issues I finished up the dyno tune and test yesterday. I didn’t see any knocks, pings, detonations or any other bad behavior. At this point I can also mention that the engine was built by Lindsey and it performed just fine, no signs of any problems and after driving the car off the dyno after 4 days of testing – 40 power pulls and many cell by cell tuning sessions – there was no odd puddles left on the floor! Even with the best of engines it is not uncommon to have a little oil or coolant on the floor of the dyno after hard use, not this time!

The final numbers –
at 19psi it made 397ft lbs@4100 and 383hp@5800
at 16psi it made 346ft lbs@4400 and 341hp@5800

The torque curve is nice and flat with a top end roll off at higher boost. The engine has some more power potential with a bigger turbo but I think this is a great street set up and I would not go with a bigger turbo just for the dyno numbers!
(the keen observers will note that he AFRs are at just below 12.5 on the 12psi chart, at 15psi it is set for 11.8-12 and at 19psi it is at 11.5 – its nice to be able to tune in great detail!)

JohnKoaWood

VERY nice.. makes me feel good about my setup...

jerome951

Nice numbers.

So, no idea why the head gasket kept blowing???

Chris White

Oh yeah, I should add that getting cars to the dyno is a lot of fun in the winter…..

Chris White

Something in the original DME/KLR or its wiring.

fast951

Chris, it looks nice. So what was the real cause of the problem?

Since the car had the problem since new, something must have been causing the blown head gasket. Did you ever determine what was defective: ECU, KLR, tuning, wiring harness, Injector(s), block/head defective???... Obviously what your customer experienced is not normal, so something must have caused it.

One more question. If the coolant pressure going over 15psi is a early sign of HG failure. Isn't the pressure from the combustion chamber entering the coolant is causing the rise in coolant pressure? So by this time the HG is damaged as it leaked already.. So the pressure sensor in the coolant serves as a warning that the HG is blown?

fast951

Chris, you hit the "post Message" before I finished typing my earlier message LOL...

JohnKoaWood

"Ghost" in the machine... odd it took 23 years for someone to figure that out.. not to mention a dozen or so head gaskets!

carlege

Ebayers be warned LOL.

Chris White

The coolant pressure sensor won’t prevent the head gasket failure – but it will stop you from do anymore damage. If you stop boosting the engine when the head gasket lets go enough to pressurize the coolant there will be very little other damage. If you keep going until the coolant temps spike you may have damaged the head, block, pistons……

BTW – if you are interested (and the customer says it OK) I can send you the DME for your expert analysis. I was told that with the new engine in place it would go into sever detonation at anything over 10-12 psi. I got the same engine running at 19psi with out any detonation.

fast951

Good idea about the coolant pressure sensor. Crisis management when something goes wrong is important. I often get calls from people, happy their engine didn't destroy itself as the problem was managed properly.

Sure you can send the DME & KLR, as long as there is no rush to test them. I will run my own software in them, then run the Motronic Monitor, data log and view all the parameters. If there is a problem it'll show. Of course, it's not a perfect test as I'll be running on a different car and using different software. Of course, the wiring harness is not getting tested either.
It would have been interesting to run the Motronic Monitor on the car with the problem.

Mike Lindsey

Wiring Harness was our conclusion. DME and KLR were sent out for testing and OK.

Mike Lindsey

We were one of many shops (including Porsche and other shops prior to LR in business) to get the car and try to figure out the problem that had been there for 20 years. We concluded after a LOT of work it's the engine harness. Probably a manufactured defect in it from the factory. The engine is just fine as Chris has shown.

Tony went EMS rather then just a harness which might of been all that it needed. There was nothing else left to test of change or test. When we say nothnig, we mean nothing.

We will post a brief tally of our experience with this car. It's hard to replay
2 years.

We are glad Chris got the job and put this long headache for Tony to rest.

Mike Lindsey

We concluded it was the harness Chris. That car had multiple DME's and KLR's from working cars swapped in an out. Also his were sent out for testing and tested good.

fast951

It'll be interesting to examine the wiring harness. I just cannot see how the harness can cause knock but no other problem (assuming there was no other reported problem). I can see how a defect of some sort in the harness can cause the ECU to keep resetting or the communications between DME/ECU getting out of sync. But I would think, running conditions in general will be affected and not just under boost. Of course, if the DME is not running WOT maps (because it's not getting the WOT signal) will cause detonation as the incorrect maps are used.

Again, it's after the fact now. The customer is getting his car now and that's what's important.