fast928

89 Turbo

Need some help here. Recently got this car from late father. Working on getting it sorted. Drove the car just a handful of times in the past, now I'm trying to get it running right. Car is dead stock with probably around 200k miles (old odometer was dead).

Anyway, this car has NO power off boost....or at least to me it doesn't. When trying to start out from stop the car hesitates (bogs) really bad. If I drop the clutch trying to get it to spin, so it won't bog....it barely spins (maybe 1/2 wheel) then catches and bogs out really bad. This isn't normal right?? I'm almost positive in the past I could roast the tires pretty easy.....not anymore!?

The car boosts fine...pulls really strong. Doesn't pull hard until about 4k rpm...so that maybe a little late...but it does pull strong when it goes. I'm going to go out and watch the "non-reliable" factory gauge to check my boost levels and RPM's now. I'll report back exactly when and what boost levels are...

I found a few vacuum leaks and fixed those...no change. Intake is tight. BPV checked out fine. Cap/rotor and plug wire are all new. Any other ideas??

TIA!

88BlueTSiQuest

How did you check it? If it's the factory Bosch one, it's probably bad, as they tend to go bad pretty quickly. Weak diaphragm style.

It also sounds like you might still have a vacuum leak somewhere. These cars aren't powerful without boost, but it shouldn't necessarily be bogging down like you describe.

Do a search on pressure testing the intake, this will allow you to find the leaks.

fast928

Pulled a vacuum on the BPV nipple. Pulled and held solid. Diaphram is definately good.

I'll find the pressure test instructions...thanks.

MM951

I'd put my money on a vac leak.


fwiw, when I adjusted my fqs switch to retard timing it was a dog off bost, stock position it felt great. might be worth checking its set at 0

zoltan944

definantly still leaking somewhere I think. The cars arent' tire burners off boost but it is a 2.5 liter!
general maintenace stuff done? like the wearable parts?

what is a FQS?

PorscheDude1

I think FQS = Fuel quality switch located in the DME.

88BlueTSiQuest

The diaphragm holds vacuum, but what about boost? You could have a pretty sealed up intake under vacuum conditions, but the minute it changes to boost pressure, things change.

My boost pressure tester consists of a ~2" PVC pipe cap(I can't remember the exact size, that's why I said to search). I have an air hose fitting attached to the cap, and I fit it into the intercooler input hose and clamp it down. I use a gauge and pressure regulator on the cap, and I pressurize the system to ~20psi. This will show you any issues you have, chase down the 'tissssss' and fix them all. Clark's garage might have all the particulars, but the site is in a limbo mode right now until the registration goes through.

My BPV actually held pressure when hooked up backwards, but when hooked up correctly, it leaked like a sieve. I ran it backwards for a week until my replacement got here.

You might find the majority of your leaks will be under the intake, as those hoses are usually brittle and old.

fast928

I think I found it. 5 of the 6 cam tower "caps" leak. They don't leak oil but they all leak enough to "blow bubbles".....some leak worse than others. Long story...but I had the cam tower powdercoated and those threads got buggered up.....badly. Guess the new threads where off just enough. I'll figure out how to seal the "caps" up and then check for more leaks.

You guys think it would leak enough vacuum there to effect performance?? I know when the cam tower seal went it ran like total crap...so I'm thinking yes.

potent951turbo

Have you done a compression test?

fast928

That will be next if fixing all the leaks doesn't do it.

fast928

Okay, still fighting this thing. Sealed the caps, no change. Still bogs horrible. It's starting to get to me!!!

On my test drive today I figured out that full boost doesn't hit until ~3800 rpm...is that right for a K26/8??

Found the crankcase vent (#2) ....
http://dcauto.gotdns.com/images/full...OG/pg_0059.jpg

I can't find anymore leaks with the vent above hissing. Will try to undo that section tomorrow to make 100% sure there are no more leaks.

Quick question...can I do a compression test w/o pulling the intake?? Looks like a tight fit! Will check this if I can find my tester but doubtful as the car was so strong before the cam tower seal went out in the Fall.

This is getting to me as the car was so strong last Fall. Now it's just sooooo weak off-boost. I'll double-check the cam/crank timing again too....for the 100th time. Anything else I'm missing? TIA!!

zoltan944

seems a bit more complex but a new TPS for me fixed alot of off boost issues as I beleive it fixed the ignition maps

fast928

Okay, I think I may have found something this afternoon. Blocked off the crankcase lines. And still heard a lot of hissing under the intake. A lot of looking and spraying and I think I may have found it. Is it normal for the cycling valve and the idle control valve to leak?? Anybody had this before??

If I spray soapy water at the cycling valve connector it blows HUGE bubbles. ICV does some at the top of the body. None of the hoses appear to leak on either valve.

Anyone seen this before?? Not supposed to leak at either of those right!?

special tool

Pull off the intake and fix these problems you have found.
These will be 90% of the problem at least.
New intake manifold gaskets wouldn't hurt either.

Spidey944

OT but good to see you ST.

Also, try unplugging the TPS and see what happens. I agree that any type of vac leaks will affect drivability, but just try this and see. Need to rule it out. I had one that failed and hesitated and stumbled horribly. It's ok to drive unplugged. If you are seeing leaks under the intake, and one of the hoses going to the ISV is cracked, it will do crazy things too. GL.