Ok, well it all started out when I put a boost gauge on a couple weeks ago and discovered I was only getting about 5-6 lbs of boost. No real apparent boost pattern... just usually a max of 5-6 lbs. So I started with the basics. Took off the airbox and ran it wide open. That wasn't it. So I ordered an offroad midpipe and put that on. That brought the boost peaks to around 7lbs, but didn't fix the overall boost problem. So I've concluded so far it is neither an intake or exhaust restriction.... Today I've been doing some other things. I tried testing the preasure the intake would hold, but must have been doing something wrong. I put tennis ***** in the intake pipes and clamped them down. Then pulled a vacuum line off and put the air nozel on the fitting. All I could hear was air moving through the motor. No apparant boost leak, it just wasn't preasurizing... the boost gauge didn't register any preasure so I must have done something wrong... But I don't think it's a boost leak because then I pulled the vacuum lines off the wastegates. Bingo, we have boost. I might not have pulled the correct lines off the wastegates though. There are 2 on each. I pulled the 2 that looked like that went to the intake manifold. Up to 4500 it'd be the same 5lbs of boost... but after 4500 you had better watch your foot because it would easily go past 10. So I'm thinking it might be related to the wastegates. Either they're bad, or not getting vacuum...

So that's what I've done so far. Not exactly sure if I've done anything to help figure it out at all... but if anyone has a suggestion I'm all ears! My mechanic thinks I might have weak springs in my wastegates that are allowing them to open up too early. Think that's a possiblilty? My thoughts are that the secondary wastegate/boost is fine once we fix the wastegate... but the primary seems to be having a hard time. Am I really supposed to have 10lbs before 4500 rpm??? And could the primary wastegates malfunctioning cause the secondary wastegate to open at the wrong time? Like I said, w/ the vac lines off the wastegates I still only get about 5lbs primary, but as much as I want secondary... I better make sure I pulled the right vac lines though, so if someone know's which one's need pulled let me know.


Hope this all makes sense. If you need to me to describe anything better just let me know...

Thanks
Chuck

 

Just another thing real quick... I just read a page on troubleshooting the sequential turbo's (home.istar.ca/~dvandit/TurboTroubleshooting.shtml) and it all makes good sense that I have a primary boost problem here. I'm not hitting the required 8psi for the secondary to function properly. I'm gonna check a couple things on the top of that list... but have a question. What/where is the Y Pipe connector hose (coupling)?

Thanks
Chuck

 

The coupler is the rubber piece that connects your crossover tube to your Y pipe. The cross over tube is the tube that connects to the top of the IC piping, the coupling should be at the other end of the crossover tube connecting right next to lower intake manifold.

 

Yeah, I figured it out shortly after I made the post. Thanks for the help!

So does anyone have any suggestions? Are there any good sites that describe in detail how the sequential turbos work? It'd probably help diagnose the system if I understood exactly how it worked...

Couple more questions. I guess there is not 2 wastegates like I thought there was.... One of those is some sort of turbo controller? It's all kind of confusing, but do those go out often? And is there supposed to be a pill on the wastegate? There isn't one on mine from what I can see, so that's why I ask...... If there is supposed to be one, and mine doesn't have one, that's probably the problem. The wastegate is just dumping all the boost too early. I'll probably do a little more testing tomorrow though. Just looking for some opinions before I dig in again

Thanks
Chuck

 

Depending on the year of your car, there will be either pills (93-early 94) or built in restrictors (95 +) in the two nipples off the compressor housing. If there are no pills in the lines, and no restrictors, then yes, low boost will occure, but 5 psi seems a little low. This could be because the precontroll door was being forced wide open, stealing exhaust gas from the primary.
You will need to replace the restrictor pills with stock pills, or holley jets, or HD swamp cooler water valves before you go on with your testing.

 

ttt

 

anyone with a pic of the wastegate? I thought the wastegate was internal?

 

Wastegate is a little flapper inside the turbo manifold. The car should boost at 10psi then the flapper opens up at 4500rpm then you get the secondary boost. It should also be at 10 psi. You should get a small 1-2 psi dip at transition.
Have you replaced all your stock Vacum lines. Because if you have not that is the first thying you need to do.

After addressing that if you are still having a problem you can track it down from there. But without knowing that all lines are still in place and sealing you can't really diagnose boost leaks. If your mechanic is not extremly experienced working on Fd's I wouldn't let him touch it. I have read numerous stories of like this where these mechanics screw up because they don't know these cars and try to apply what know of NA pistons to our Turbo charged Rotaries.