Bad Wastegate Actuator?

[jimmie-d]

I'm relatively new to the turbo scene. I have an 87 GN with 38,000 miles, 36# injectors, RJC distribution plate, Poston hot-wired fuel pump, Bosch adj FPR, Poston Headers, TT 91 chip, Razors alky injection running straight methanol, Cotton's high performance coil pack, 3 1/2" intake pipes on stock turbo, stock tranny with cooler, stock converter, SE Turbo manual boost controller.

Two weeks ago I took it to the track for the first time and I could only get 15 lbs of boost. I ran 13.6 at 100.345. A few days later I got some help on my manual boost controller and got it installed correctly so it worked. I took it out on a back road inching up the boost with a target of 23. I got to 23 no problem, but shortly after flooring it I got a loud pop under the hood, the boost went to zero and the car really slowed down. It scared me because I was afraid I had blown up my motor.

When I raised the hood, I found the hose going into the throttle body had come off. I stuck the hose back on, minus the clamp that was missing and drove carefully home. When I got home I reclamped the hose tightly and found four vacuum lines had also come off. I clamped all them with the black plastic cable ties and thought everything was fixed. I thought I just didn't have the clamp tight enough and the 23 lb boost blew it off.

I didn't drive the car again until last Friday when I started getting it ready to go back to the track. The car ran nice and smooth until I got on it. At 10 lbs I got the same loud pop and when I looked under the hood I had some more vacuum lines off.

One guy with a lot of turbo experience told me he thought it was a bad wastegate actuator. His suggestion makes more sense to me than some others I've been told.

Can a bad wastegate actuator cause this? I had to miss our Buick/Ford Shootout this weekend because of this. Can anyone help me out with this?

Sorry for the long post, but I wanted to give you all the facts.

Thanks,
Jimmie

 

[TurboDave]

NO a wastegate actuator wont cause intake backfires. Especially since one happened at only 10# of boost.

Something else is going on in there to cause those backfires. Since you're running alky there are those that might suggest removing the power plate, in the thoughts that alky could be pooling on it and causing such occurances. Couldn't hurt to pull the power plate out just for troubleshooting and see if the.
23# of boost does seem a bit much, evne with alky, for a 91 chip.

 

[scot502]

Hello my car did same thing and i changed plugs, wires, coil pack ,and no more pop.GOOD LUCK.

 

[XLR8]

Make sure all your hoses are tightly clamped and all vac lines zip-tied. If the vac line blows off of the MAP sensor the alky system sees no boost and gives no alky, and at 23# of boost on pump gas with a 91 chip you will most likely damage the motor.
After all lines were secure I would lower boost to 10# - 12# and start working my way back up to your target. You do have a scan tool - right?

 

[DailyDrifter]

I'm with Turbodave. If its popping out the intake its running lean. Is your fuel psi set? I would back down the boost a little until you find the problem. What kind of MAF do you have?

 

[jimmie-d]

Thanks, I'll try that.
Jimmie

 

[jimmie-d]

NO a wastegate actuator wont cause intake backfires. Especially since one happened at only 10# of boost.

Something else is going on in there to cause those backfires. Since you're running alky there are those that might suggest removing the power plate, in the thoughts that alky could be pooling on it and causing such occurances. Couldn't hurt to pull the power plate out just for troubleshooting and see if the.
23# of boost does seem a bit much, evne with alky, for a 91 chip.

I'll try removing the plate and see what happens. What maximum boost would you recommend with the 91 chip and alky?

Thanks,
Jimmie

 

[jimmie-d]

I'm with Turbodave. If its popping out the intake its running lean. Is your fuel psi set? I would back down the boost a little until you find the problem. What kind of MAF do you have?

I set the fuel pressure at 43# as recommended by TurboTweak. I have an LS1 MAF.

Jimmie

 

[DailyDrifter]

I would go down to 17-18 before something goes bad. Do you have any scan master numbers? With alky and a chip burned for alky i'm sure you could go above 25psi ASSuming all is well with the rest of the sensors.

 

[jimmie-d]

Make sure all your hoses are tightly clamped and all vac lines zip-tied. If the vac line blows off of the MAP sensor the alky system sees no boost and gives no alky, and at 23# of boost on pump gas with a 91 chip you will most likely damage the motor.
After all lines were secure I would lower boost to 10# - 12# and start working my way back up to your target. You do have a scan tool - right?

I've zip-tied all the vac lines, tightened all clamps. I have a scan toll & TurboLink but I had to order a new cable to hook it up to my laptop.

Thanks,
Jimmie

 

[jimmie-d]

Hello my car did same thing and i changed plugs, wires, coil pack ,and no more pop.GOOD LUCK.

Thanks for the suggestion. I've already changed all those with no results.

Jimmie