legacycentral bbs

After about a year of sitting I finally got around to doing some work on my '92 Turbo wagon with 248,000 Kms (154,000 miles).

I replaced the starter last year and was beside myself when the cooling tank nipple broke. I replaced the tank with a new one, somewhat comforted by the fact that it is a common occurance and would have failed some time later. I think I got all the nipple bits out of the hose!

Some coolant spilled onto the knock sensor like many others giving me CEL code #22. I found a used old style (I know but they are $120 cdn here) sensor and cleaned up the block with sandpaper and voila the CEL was cleared.

I fired her up today and everything seemed normal. I drove it around the block and saw white smoke rising from the chimney. I don't hear metal grinding noises (yet). I drove it for a while longer and it seemed that the smoke dissipated, then I took it for a brief run on the highway. The smoke returned when I was stopped at a light.

The turbo has always had a different issue before I parked it. It spools up normally when accelerating then it cuts out and makes some noise till I let off the gas. Then it spools up again. I have read about the hesitation but I seem to think this might be different. Maybe a wastegate or BOV problem? I'm just wondering if these problems are related and should I still be driving the car?

Bob

What color is the smoke?

If it's whitish, it might just be coolant that splashed onto the turbo, exhaust, or engine that's slowly burning off.

The other issue -- what exactly is it that's "cutting out?" Could it be the fuel injection system cutting fuel? You might be experiencing overboost fuel cut (either because of a sensor problem or a malfunctioning wastegate). You should buy a boost gauge or build my scantool and figure out what's going on with boost. Overboost is definitely bad for the engine, and fuel cut at boost is also definitely not something you want to do a lot.

The smoke is white. That makes sense that coolant would be burning off.

Where do I find how to build your scantool? It does seem to me that the fuel is cutting on boost.

Bob

Yeah, it's probably just coolant. You can try gently rinsing off the area that coolant spilled onto to see if you can get rid of most of it.

Read the first sticky thread in the Electrical forum for information on the scan tool.

So do you think it might actually be fuel cut? The scan tool can report injector pulse width so fuel cut'll show up as a minimal pulse width.

Excellent, thanks!

I'll be hacking up some old printer cable tonight!

Bob

I get white smoke too but I dont have any coolant spilled or anything. Almost smells like oil. Think the seals are going?

Where is the smoke coming from? It's not uncommon for valve cover seals to fail, allowing oil to drip onto the exhaust, where it burns and rises out of the engine bay.

You are absolutely right! The smoke is coming from the exhaust. I failed to mention that I did replace the PS pump and must have spilled a little fluid onto the exhaust.

I just cleaned around the exhaust today and will see if the smoking returns. It may still be the valve cover gaskets.

I built the scan tool cable and hooked it up today. That is awesome! I found out I was only getting a maximum of 4.2psi of boost. During acceleration the boost would peak at about 4.2 and then decrease fluctuating between 3 and 3.5psi. (I live in Calgary which is 1,139m elevation)

I did notice that the ignition timing was being retarded quite often. Could this be bad gas?

It does sound to me that the turbo is louder and not as smooth as it should be. I also see what looks like oil buildup around the turbo housing. I am thinking this has been going on for a while.

Bob

Hmm. You shouldn't be getting such low boost, unless maybe you have a very restrictive intercooler setup or something.

What does it say manifold pressure is at vacuum?

I think you should buy a boost gauge to verify those numbers. Your pressure sensor might be faulty.

The car is completely stock.

The pressure at idle is -18.5 to -20 inHg (fluctuates a bit).

I just filled the tank with fresh premium gas today. I hook up the laptop and the boost is now in the 8PSI range.

If I step on the gas what should I expect to see in terms of boost pressure? A slow rise to maximum boost and then backing off?

Bob

That seems like an appropriate idle pressure.

Hmm. Maybe your wastegate actuator spring is just worn out, so minimum boost is much lower than it used to be.

Boost behavior depends a lot on the circumstances... If you're at high RPM in almost any gear, flooring the gas pedal should fairly quickly build up to full boost and stay near it. If the car's idling out of gear, flooring the pedal will give a split second of boost before you have to back off.

A bad cat in the DP might make your boost lower. When I replaced my DP I had much better throtle response because the turbo could spool up faster.

Yes, an exhaust (or intake) restriction can prevent boost.

But then how would the ECU be able to bring boost back up?