pyropete125

Hi all,

I did a DE in my track only 924S and found out that I have a problem- no power after 4500ish and 4th and 5th on the straight there was no difference in pulling.

2.5 NA 165psi in 1,2,3 and 150psi in 4 - no leak down test yet.

Starts up fine and idles great, free revs nice. Sounds fine mechanically. Not burning oil, or any soot at the tailpipe.

New fuel pump, fuel filter, and injectors. Fuel pressure perfect.

I have a wide band oxygen sensor and the A/F ratios were fine. I have the narrow band output hooked to the DME and when I shut off the gauge during the event it ran slightly better- so no O2 input- slightly better.

I oscilloscoped the coil output and nice even timed wave function.

I did take out the thermostat (before the DE) and I was only getting 145* temps. I am going to put a restrictor in to slow down flow.

I tested the air meter and DME in a different car and they work fine.

Would a broken WOT switch in the throttle position sensor cause this? I'll be checking this weekend.

I am going to double check the timing marks- I have done the belt on many 924/944 but maybe I was off on this one- first time for everything.

Any other ideas?

Thanks
Pete

Humboldtgrin

I was thinking cam timing right off the bat. Yes there is a first time for everything. I can't think of anything else that would effect high RPM performance. And seeing how you just did the belts that's most likely it. i set my turbo cam timing wrong one time(long ago) and it acted like an NA engine. Never built boost. Fixed the timing and had a ton of power after that.

kevin12973

Is it like this cold as well as hot?

grenadiers

When idling, pull each injector plug to see if there is any difference in idle. Mine did this, ('88 924S) and had a faulty connection. When I ran my first DE with this car, I thought, hmmm, this sure is a dog~!

pyropete125

As best as I can tell the timing belts are right on.

I am going to do a leak down test in a few days. This motor may just be tired, I have no idea what the previous owner[s] did with this car, but it was stripped out with a 4pt bar and harness....

When it is hot at the track I only had about 10psi oil pressure at idle, but 4 bar when running hot or cold. 3-4 bar start up cold idle.

I may swap in a 16v 3.0 motor but I am just weighing my options vs gain and the cost. I am going to start another thread about swapping it out.

Thanks
Pete

pyropete125

Timing belts are spot on, but #4 cylinder has ring blow by bad- like 40% on the gauge I used... the other cylinders were about 10%.

Looks like I am going to swap out for another 8v 2.5 NA I have.I think I will do a 16v 3.0 this winter.

The car showed signs that it had been under water or in a flood before I bought it and I think it possibly sat for some time with some water in the #4 cylinder. I bought it before the flooding from Sandy.

I am surprised it ran as good as it did in the lower RPM's.

Thanks all for the suggestions.

Pete

car_slave

In another post you said you're running a 951 gearbox. That could be the problem...

ddombrowski

>When it is hot at the track I only had about 10psi oil pressure at idle, but 4 bar when running hot or cold. 3-4 bar start up cold idle.

That doesn't sound good to me. You probably know more about these engines than I do, but that seems excessively low to me. Weird that you don't burn oil. We peg the oil pressure gauge at cold start, and at its hottest we idle at 3.5 bar with 4-5bar at 1500 rpm, but we eat 1/2 quart per hour.

If you were at WOT and you had a broken WOT switch, I'd think that would result in a lean condition if you're lean enough to really drop in power.

How is WOT past 4500RPM in 1st,2nd,3rd gear?

Also, while on the topic - i skipped through your pictures on picasaweb. Did you use some aftermarket/universal fuel line/pump/fittings in the rear? I had considered switching the fuel pump/filter setup to something more universal I could find parts for at an auto parts store (rather than the porsche specific lines/fittings that are expensive) but didn't know if a hose clamp on the high side of the fuel pump would be good enough.

pyropete125

Universal inline walboro 255lph gss ### with barb fittings. You can use the outlet with the banjo fitting even.

Humboldtgrin

I just posted and had to reread. Tiered engine and 951 gears. That's makes sence to have no power on taller gears at higher RPM's. I was thinking a clogged fuel filter would do the same thing too.

porscharu

I'm guessing since it is track only you are not running a cat?