1992 Typhoon Wastegate overboost problem


Quickstop
02-01-2006, 06:02 AM
Hi,

I am just about to purchase a 1992 Typhoon (sorry no VIN/mileage yet) from my father which we have owned as a family since the car came into existence.

It has a couple of problems though and I was hoping someone here might be able to help.

1) Wastegate overboost

The engine performs well but when you put your foot to the floor the turbo spools up and then after a couple of seconds the engine cuts out and you have to restart it. The ECU has been replaced along with several cables. Normally the engine runs fine so I am inclined to think that the wastegate is not working. The boost builds up and then the ECU cuts out. I believe that the wastegate is not stainless steel and therefore could be deteriorated and causing this problem.

Has anyone had a similar problem? Can I get a stainless steel wastegate or an alternative from somewhere? Do I need to replace the turbo? What alternatives are there? Would I need a new ECU then?

2) It has a stainless steel exhaust but the only parts that aren't stainless are the exhaust manifolds. Has anyone replaced the originals with stainless manifolds? Where can I get some?

Any other suggestions or comments would be greatly appreciated.

regards,

Q

PS I will duplicate this on www.syty.org (http://www.syty.org)

turbodog
02-01-2006, 08:46 AM
Hi, there are a few things to check.
1. locate the boost control relay and unplug it. Now, if the problem was related to ECM, wastegate plumbing or wiring, it will go away and boost will be limited to ~8psi 'base boost'.
In this case, first inspect the small tubing and elbows that connect the wategate solenoid (mounted on the turbo) to the compressor and wastegate actuator. The elbows tend do heat-harden and fail. These tubes are under pressure (not vacuum) so they can also blow off the nipples. The wastegate solenoid is the next thing to check. Its sort of hard to test, probably better just to spring for $15 and buy a new one. Only suspect ECM or wiring after absolutely ruling out the stuff above.

2. if problem still exists with the relay unplugged, you probably have a stuck waste gate. See if you can move it freely by hand. If you can, it may only stick when hot. Yes, you need to do it. Removing the fenderwell gives free access, so you can get it hot and check it without getting burned. If it moves freely, then it probably just needs to be adjusted. Lengthening the actuator rod decreases boost.
Also, if you have a stainless exhaust system, it is not stock. You sure the cat converter has not been removed or gutted? This is a sure way to cause overboost.

If you don't have the manuals, etc to locate this stuff, you need to get them. Very few people know how to work on these trucks, so you should learn it yourself. Go to www.sportmachines.com to get a CD with all the relevant manuals on it, and go to www.syty.net and search, lots of info there.

Hope that helps.

Oh, and on the manifolds... you can get stainless headers at www.raceprovenmotors.com. Very pricey. Most folks just live with the iron manifolds (and some run the 1/4 mi in the 10's doing so!) or get them ceramic coated.

Quickstop
02-01-2006, 09:39 AM
Rick,

thanks for getting back to me so quickly.

One thing I forgot to mention is that it is a Saudi Typhoon (we lived there!).

My father put on the custom exhaust and then changed the chip to the US unleaded chip. Is it meant to have a cat in that system?

Could this be the problem?

I am going to order the manuals as well and a new solenoid. Where is a good place to get one?

I have also been advised to check the vacuum hose to the wastegate in the syty forum. Where can I get decent hoses?

I am based in the UK.

Again, many thanks!

Mark

turbodog
02-01-2006, 03:33 PM
You can run with no cat, or you can run an aftermarket (freer flowing) exhaust - but generally not both - without overboost problems. The boost spikes up too fast, the ECM is too slow to respond and/or the wastegate does not flow enough to avoid the boost spike.

Solutions include:
- porting the wastegate of the turbo. There is a how-to online somewhere.
- going to an external wastegate and tying/welding the stock wastegate shut.
- going to a bolt-on aftermarket turbo with a larger integral wastegate

The tubing for the wastegate actuator can be replaced by simple silicone vacuum tubing, but must be clamped on (small ty-wraps work fine for me). The whole harness can still be bought from GM (I think) but is pricey. Hmmm, not finding a GM part #, maybe it is discontinued. The solenoid is a GM dealer item, GM #1997152. Or, for internet purchasing, try http://www.gm-auto-parts.com/parts.htm.
For part numbers, etc http://www.sytyauthority.net is a good place to look.

keep us posted, I'll check in regularly and help out if I can.

Quickstop
02-02-2006, 09:27 AM
Turbo,

cheers for the continuing support!
Also I noticed the raised profile of your hood. Custom turbo? What have you done to your Ty?

cheers,

Mark

turbodog
02-02-2006, 11:12 AM
Hood is a 2-inch cowl induction fiberglass part. I don't know the manufacturer, but many companies make them, in 'glass or steel. Probably the premier manufacturers are Harwood and Goodmark. I got this one at a very good price -$0-, but it has a bad paint job on it that I have yet to correct.

I am running the OEM turbo.

Mods:

STG 'ultimate chip' (allows selection of max boost and timing advance)
Hi-flow fuel pump
Adjustable fuel pressure regulator
relocated battery (to driver side) and air filter w/ K&N element (to pass side)
auxilliary IC heat exchangers and aux. IC pump
Steel IC coolant lines switched to hose and re-routed away from heat sources
Plastic air scoop for stock IC heat exchanger
Trans cooler mounted behind stock IC heat exchanger
Remote starter solenoid
ATR 3" exhaust and 3" hi-flow catcon.
Front coil-over suspension conversion
ZQ8 steering gear (actually a "WS" code camaro box)
Custom steering intermediate shaft (eliminates rag joint)
Rear springs re-arched, 2" lowering blocks, modified electronic levelling system
late-model Camaro brakes front and rear
Corvette ZR1 (Gran Sport) wheels, 17X9.5 front, 17X11 rear
3 guage pillar pod with 4 temp guage inputs, 4 pressure guage inputs, and separate boost/vacuum guage.

Quickstop
03-04-2006, 01:26 PM
Turbodog,

I am now the proud owner of a 1992 white GMC Typhoon! Very pleased.

OK, the problem:

I messed around with the wastegate as the actuator appears to be sticking.

1) Drove car in the morning and the boost would cut out .

2) Later that day, tried to move actuator but it was stiff and appeared stuck almost.

3) Set it fully to the rear (wastegate open) and no problem with the ECU cutting out. Turbo took a little longer to wind up but it eventually got there though it did feel a little less powerful than I was hoping for.

4) Tried it with wastgate actuator closed (fully forward?). Power was not as good, but it still didn't cut out. I was expecting loads of power, quick response with quick cutout - not what happened at all.

What could be the problem?

Is it a vacuum operated wastegate or an over pressure wastegate?

Is the solenoid activated to close the turbo, or does the solenoid move the actuator? Where can I get detailed info on how to fix it?

I also need a MPH display for the dashboard / console. I have loads of questions now, but love my new car. Pictures to follow!

cheers,

Q

turbodog
03-05-2006, 08:36 AM
Congrats on the purchase! Be patient and get it running right before flogging it. Definitely sounds like a sticky wastegate. Your (extreme) adjustments should have produced very low boost (rearward) and crazy overboosting (forward). Do you plan to work on it yourself (highly recommended)?
Lots of info to catch up on... go to www.syty.net, search for answers and join the community!

a good explanation of the wastegate system are here:
http://www.geocities.com/w_bowley/Green/boost2.html
and here:
http://www.chitownsyty.net/html/tech/boost.htm

also go to www.sportmachines.com and get the service manuals on CDROM.
Feel free to check back in here if you want, I'll help any way I can. Was this a Saudi Ty? Thus the need for a instrument cluster? Where are you located?

Rick

Quickstop
03-05-2006, 12:56 PM
Rick,

cheers for your input! Mycha appreciated as always.

OK, so i drove it back today and I now have a couple of questions...

At around 160kph there was some serious knocking so I backed off immediately. How can I resolve this? i did have my foot to the floor (only a couple of times - honest!)

I read those two sites that you gave me, but there wasn no mention of how to fix a sticky wastegate? I am planning on doing as much work as ican myself as I don't really trust anyone else - nobody knows these cars really.

So, do I replace the wastgegate which is integral meaning I probably need a new turbo, in which case which one to get?

Can I take the wastgate mechanism apart and fix it so it is easier?

Should I seal it open and get an external wastegate and mount it?

I'll be on the syty forums as well looking for parts. I can't wait and I love my new car.

I'll have some pics up soon I hope.

cheers,

Mark

turbodog
03-05-2006, 05:30 PM
As for the sticky wastegate... just have to get it off the truck, and investigate. Probably carbon buildup, nothing some emery cloth or a file can't fix. Search and you'll find instructions on 'porting' the wastegate. You would probably want to do some of this while you have it apart. You can have the turbo rebuilt, and a reputable shop should fix the wastegete while they're at it. If going to an aftermarket turbo, there are a million and one choices. It should be well down on your list after getting the truck running perfectly. If you determine the turbo really is toast, and you insist on an upgrade, I recommend contacting Raceprovenmotors.com or detroitturbo.com for advice.

Knock is the absolute evil killer of these trucks. Do NOT go WOT until you have it under control. If you can hear it, it is too severe for the spark retard to compensate, and your engine is in immediate peril.

1. make sure you are running at least 92 octane fuel.
2. make sure your intercooler is operating properly. The stock pump is a common failure item.
3. pull the plugs, check for lean fuel or oil contamination indicators.
4. check fuel pressure.
5. replace fuel filter
6. check timing
7. replace plugs, wires, cap and rotor (this should be on your list of 'make it right' items anyway, along with the fuel filter)
8. get a scan tool and monitor knock religiously until you have it solved.

enough for now.....

Quickstop
03-06-2006, 06:11 AM
Rick,

point taken so here goes...........

1. make sure you are running at least 92 octane fuel.

The fuel I am using is:BP unleaded = 95 octane, though I can get it at 97 rating. Price is pretty steep at $6.50 per gallon though! Am in the UK.

2. make sure your intercooler is operating properly. The stock pump is a common failure item.

How?

3. pull the plugs, check for lean fuel or oil contamination indicators.

Will do - am reading the service manual

4. check fuel pressure.

Tips? Again, am reading the service manual.

5. replace fuel filter

Am going to order one right away.


6. check timing

Need a scan tool for this I guess?

7. replace plugs, wires, cap and rotor (this should be on your list of 'make it right' items anyway, along with the fuel filter)

Any good places to get this stuff from?

8. get a scan tool and monitor knock religiously until you have it solved.

Any recommendations as to which one?

The engine is running fine as long as I do not try an accelerate too fast at high speed. Like you suggested, I will worry about the turbo when the rest of it is all sorted.

Thanks for being patient. I know I am asking a lot of questions but you clearly know your stuff!

Regards,

Q

turbodog
03-06-2006, 09:15 AM
2. make sure your intercooler is operating properly. The stock pump is a common failure item.

How?
Open the small 'radiator' cap on the upper IC. Should be full of coolant.
To test your IC pump, put a paper clip between pins A and B of the ALDL
connector. Turn the key to ON (but don't start the truck). This will force
the intercooler pump on. Then go to the front of your truck and listen for
the pump ... or put your hand under there on the pump (lower back side of lower IC, a.k.a CCHE) and feel it to see if it's running.

If you need a diagram of the ALDL connector, look at the following page:

http://www.sportmachines.com/maintenance/aldl.html

BTW, the stock pump uses Black as positive and Brown as negative. Bass
ackwards.

4. check fuel pressure.

Tips? Again, am reading the service manual.
May be difficult to find locally, but most auto parts shps here will sell a shop fuel pressure guage for around $40. It attaches to the schrader valve on the driver side fuel rail. Pressure should be ~42 psi at idle with the vacuum line to the fuel pressure regulator disconnected and plugged. Then with the vacuum line attached, pressure should go down around 8 - 10 psi at idle.

6. check timing

Need a scan tool for this I guess?
You will use a standard timing light. Best to
'bump' the starter and get underneath, look for the timing grooves on the harmonic balancer. 'Bump' again, keep trying till you see it. There are actually 2, about 30 degrees apart. Hard to tell which is the right one, so mark them both with white paint, etc so they stand out more clearly under the timing light. Then, go to the passenger side footwell and peel back the top front edge of the carpet. Find a lone tan wire with an inline connector. Disconnect it (this disables the electronic timing control). Then use the timing light as you would any vehicle (#1 plug is front driver side plug, shoot the light diagonally down from top driver side, be careful of the fan!). With the wire disconnected as stated above, timing should be 0 degrees, TDC. If it needs adjusting, you will need a proper distributor wrench or a wobble extension. The distributor clamp bolt is a pain to reach.

7. replace plugs, wires, cap and rotor (this should be on your list of 'make it right' items anyway, along with the fuel filter)

Any good places to get this stuff from?
I would recommend you contact Mike Hood and tucker auto parts:
tucker@tuckerautopartsonline.com
He's a great guy, has good prices on top-quality ignition wires, etc... he will probably track down a cap and rotor for you (you want a top quality unit with brass conductors) even if he doesn't stock it, and will work with you on international shipping.

8. get a scan tool and monitor knock religiously until you have it solved.

Any recommendations as to which one?
Bare minimum is a unit from AutoXray.com (I use one), but there are much nicer tools for use with a laptop if you own one. Probably best to 'search' at syty.net for 'scan tool' and read up before you decide which one.

The engine is running fine as long as I do not try an accelerate too fast at high speed. Like you suggested, I will worry about the turbo when the rest of it is all sorted.

As long as it is stuck open, you're pretty safe.

Thanks for being patient. I know I am asking a lot of questions but you clearly know your stuff!

Well, I have about 250k mi in Typhoons, doing all wrenching myself. I know the standard maintenance and repair stuff, but when it comes to performance mods, I am not an expert. There are many folks at syty.net who are, however.

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