Sudden loss of boost

[MCH86GN]

I'm running into an issue I ran into last year. I go to WOT boost will hit 20 - 25 PSI and the wastegate opens and dumps the boost. Last year it was thought to be a fuel pump issue, where the fuel pressure was raising proportionally to the boost. So fuel pump was replaced, 255 and volt booster added. Volt booster activates at 10psi. This seemed to take care of the issue.

Happening again, with sudden loss of boost. However, I'm monitoring the fuel rail pressure and it is raising as I build boost. However, I haven't gotten a chance to test it above 15 psi. It would be nice to figure out.

Sometime this fall I will be replacing my current block with a rebuild 109 stroker.

 

[SHADOWII]

Are you running the stock w/g, solenoid and "Y" to the turbo? Where is the boost gauge connected, to the map line or directly to the intake? When I first started mod'g my 86, it would go into an over-boost condition and dump the w/g also. After some troubleshooting I went tuner-style, replacing the stock system w/a Q-boost controller. You might want to use a mity-vac or similar to check for leaks in the vac. lines and wire-tie the hose connections to keep them from blowing off under boost.

 

[MCH86GN]

Are you running the stock w/g, solenoid and "Y" to the turbo? Where is the boost gauge connected, to the map line or directly to the intake? When I first started mod'g my 86, it would go into an over-boost condition and dump the w/g also. After some troubleshooting I went tuner-style, replacing the stock system w/a Q-boost controller. You might want to use a mity-vac or similar to check for leaks in the vac. lines and wire-tie the hose connections to keep them from blowing off under boost.

I'm using the stock setup. Not sure where the boost gauge is connected, I would have to trace it from the cockpit. I will check into an after market boost controller and I will also check for vacuum leaks. I have most of my vac. lines wired tied.

I have a list of things I'm going to check. One thing I'm going to do is to switch back to the stock style PCV and for the time being remove the RJC PCV. I know this isn't the cause, but my idle BLM is 142. I'm also going to turn my boost down to stock level and see what happens.

One last thing, has you ever heard of a HD wastegate failing. I realized when I was turning down my boost yesterday that the rod going into the wastegate was turning as well. I need to using some channel locks and loosen the 7/16 nut.

I have $7k rebuild going in, not including cost for turbo and a few other things. I have to get these bugs ironed out. Otherwise I will have an expensive brick in the garage. I won't take any chances once my rebuild and rebuilt trans are installed.

 

[SHADOWII]

The w/g rod should not be rotating. If you have a mity-vac, you can check it's operation. I tried the heavy duty w/g for a while, but didn't like that it was too difficult to control the boost. It would shoot to 30#s in an instant. So I went back to the 7# one.
I understand the cost of upgrading and rebuilding these cars as I am doing some myself. I'm trying Mike Licht's new piston design in my stroker, replacing the je's w/the diamonds. The diamond's are almost 300 grams lighter than the JE's @ .020" over!?

 

[MCH86GN]

The w/g rod should not be rotating. If you have a mity-vac, you can check it's operation. I tried the heavy duty w/g for a while, but didn't like that it was too difficult to control the boost. It would shoot to 30#s in an instant. So I went back to the 7# one.
I understand the cost of upgrading and rebuilding these cars as I am doing some myself. I'm trying Mike Licht's new piston design in my stroker, replacing the je's w/the diamonds. The diamond's are almost 300 grams lighter than the JE's @ .020" over!?

I ordered the MV8500 Silverline Elite Automotive Kit. It's the hand pump with a gauge. I think it should be able to do the job. Min pressure -25psi and max pressure 30psi.
Interesting I ordered the same piston for my build, except it is .030 over. Unfortunately, Diamond shipped the wrong set of pistons. However, they're taking care of it.

 

[SHADOWII]

I ordered the MV8500 Silverline Elite Automotive Kit. It's the hand pump with a gauge. I think it should be able to do the job. Min pressure -25psi and max pressure 30psi.
Interesting I ordered the same piston for my build, except it is .030 over. Unfortunately, Diamond shipped the wrong set of pistons. However, they're taking care of it.

The MV8500 should do the trick for you. Did you get the coating on yours? Due to the lighter wt. of the pistons, I figured the added protection would be necessary.(As long as it doesn't melt the alum. heads first!! lol

 

[MCH86GN]

The MV8500 should do the trick for you. Did you get the coating on yours? Due to the lighter wt. of the pistons, I figured the added protection would be necessary.(As long as it doesn't melt the alum. heads first!! lol

I don't think I got the coating. I probably should have, but what's done is done. I expected to my rebuild done by end of July at latest, but at the last moment I changed my mind and went with a new set of GN1 over my current Champion Ported Irons. I could have gotten away with the ported irons, but I wanted to drive my car this summer.

I won't get the mity-vac tool for another week or two. Question though, do I need the one that will pull a vacuum and pressurize the system of just pull a vacuum? The one ordered does both, however, HF carries a mity-vac that will just pull a vacuum for about half the price.

 

[SHADOWII]

Both would be better as there are times when you will need it.

 

[MCH86GN]

Both would be better as there are times when you will need it.

I have 90 days to return the one I currently have to HF. Hopefully this weekend I will be able to spend sometime figuring out what the issue is.
I'm going to check the vacuum lines off the vacuum block. If I detect no leaks, I'm going to double check the voltage at my fuel pump. Even though my fuel pressure is raising proportional to the boost.
I'm also going to check my crank sensor and make sure that it has not moved. I replaced the stock one last year with a Borg Warner one, only to find out that my balancer was lose and this in turn was causing the reluctor blades to move forward and no longer be detectable by the hall effect/crank sensor.
If see nothing there, then I'm going to hook up my laptop and collect some data with the PL. Try and see what exactly is going on when the boost drops.

 

[SHADOWII]

What make chip are you running? Is it a tt?

 

[Ed Valvo]

Define boost dropping? At WOT shoots to 25 PSI then settles down around 18-20 PSI? Or drops to zero?

 

[MCH86GN]

Define boost dropping? At WOT shoots to 25 PSI then settles down around 18-20 PSI? Or drops to zero?

At 20 or 25psi it will drop to zero and you hear a loud pssshhh.

Ran into a similar problem last year and my fuel pump was replaced and a volt booster was added and that appeared to resolve the issue. Once this issue was fixed, I kept having intermittent stumbles. I ordered a new crank sensor and when I put the new crank sensor on I noticed that the reluctor blades weren't penetrating into the crank sensor ridges. I pulled the serpentine belt and I realized the balancer was loose. I rented a torque wrench and torqued it too its required torque of 219ft-lbs. By that time winter was here and it was time to park it.

As I mentioned, the fuel rail pressure is raising proportionally with the boost.

When this occurs, which is every time I floor it, and I hit the recall on my scanmaster, it doesn't show any retarding of the spark.

 

[MCH86GN]

What make chip are you running? Is it a tt?

TT 6.0, w/WB O2 sensor. I need to update my signature to show what I'm running.

I need to gather some data, I'm going to try to do it this weekend.

One other thing, I have a break out harness and data acquisition tools(laptop National Instruments 4 channel DAQ) which will allow me to probe and gather data on my crank signal, during one of these events if necessary.
I bought the break out harness from Casper's.

 

[Ed Valvo]

Sounds like a car I had with massive turbo compressor surge. Not the pff, pff kind when you go part throttle of lift when you're in boost. Felt like engine just shuts off once the boost builds and then dies. When I lifted the gas pedal, it would run normal again. What kind of turbo do you have?

 

[MCH86GN]

Sounds like a car I had with massive turbo compressor surge. Not the pff, pff kind when you go part throttle of lift when you're in boost. Felt like engine just shuts off once the boost builds and then dies. When I lifted the gas pedal, it would run normal again. What kind of turbo do you have?

TE44 with Champion Ported Irons, running alky injection.

 

[MCH86GN]

Sounds like a car I had with massive turbo compressor surge. Not the pff, pff kind when you go part throttle of lift when you're in boost. Felt like engine just shuts off once the boost builds and then dies. When I lifted the gas pedal, it would run normal again. What kind of turbo do you have?

Mine sounds similar to that, but I have ran this combination for 7 years. Oh, one difference, I have a Precsion SLIC.

 

[SHADOWII]

I don't believe this is applicable, but when the ambient temp's would get into the 40's, my alchy would blow out the wick and the car would fall on it's face. Could you be putting too much alchy through it?

 

[MCH86GN]

I don't believe this is applicable, but when the ambient temp's would get into the 40's, my alchy would blow out the wick and the car would fall on it's face. Could you be putting too much alchy through it?

Could very well be. Think about it, my car was tuned at 13.0v, after the fact I added a Casper's volt booster. I'm sure I'm pumping more alky at 15v than at 13v. Not sure how to solve this one, because I thought only the ramp rate was adjustable on the Razor kit, not the volume sprayed.

I did a vacuum check, pulled the lines off the vacuum. I didn't check the PCV, I will though. The one next to the PCV has a tiny leak, meaning it will hold vacuum but it will leak down a little more than a psi in one minute. This is the line to the MAP sensor and boost gauge I think. The middle line, I couldn't get to hold any vacuum, not sure if this is normal since it is running through a check valve which I managed to break. Headed to AZ to see if they have a suitable replacement. The other two vacuum lines worked like a charm. They held whatever number I checked, -5hg, -10hg to -25hg.

I have not been successful in testing the wastegate. I can't get the line off at Y or wastegate. Once I'm able to get the line on I will pressurize the wastegate and see if it working properly. I got the 8500 mity-vac, so I can do that now. I'll get back with you.

 

[MCH86GN]

Tonight I plan on hooking up my powerlogger and getting some data.

 

[MCH86GN]

Tonight I plan on hooking up my powerlogger and getting some data.

I didn't get a chance. I'm going to work my car this entire weekend. I also figured out way, with a check valve, to activate my Red Armstrong(not Caspers) volt booster with building 10psi of pressure in the vacuum line hooked up to it and unplug it from the vacuum lines altogether. Just hook the check valve up such that air flows though, but not out on the volt booster and pump it up with my mity-vac to 10 PSI.

Hopefully I have some answers by Monday.