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Old 08-27-2007, 08:15 AM   #1
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So, for some time now my Greddy kit has been giving about 3 or 4 PSI instead of the 6PSI that I had from it when I installed it over two years ago.
I went on a 500km drive with a buddy to collect a 91 Mk1 for him (who's going to Turbo it as well). On the way back the boost when right down to about 1PSI and the Turbo was kicking in at about 4200 - 4500 RPM instead of 3600'ish RPM. The hotter the engine the worse it is - less boost given at a higher RPM etc.
I just took the Turbo off the mani/downpipe (only 1 bolt broke ) and gave it an inspection.
Seems to be fine, wastegate is in place and flaps manually without probs.
No play in the shaft.
No warping of the mani as I had it cut before the install etc.
I'm thinking the actuator is shot
Any way to test it off the car ?
If the actuator is shot would it be causing this ?
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Old 08-27-2007, 08:34 AM   #2
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(PS) There are NO leaks BTW !
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Old 08-27-2007, 08:45 AM   #3
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Stand next to your car with the motor on. Manually check by revving your motor while you look at the waste gate rod. [Does it move at all?]
How is your overall vacumm at idle? (should be around 20)

Either that or you have a leak in between your Turbo and the Throttle Body.
On my car, I found that I had developed a huge leak between the TB and Turbo. This was not obvious to the eye because it was undeneath and of course would only open up under increased RPM's.

Last edited by LOLA - 92; 08-27-2007 at 09:14 AM. Reason: Okay - I thought I'd bring it back - Even though you swear there is not a leak!
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Old 08-27-2007, 08:52 AM   #4
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Actuators do go bad over time... but we're talking 10 or 15 years, not two usually. Reinstall everything and go for a drive. If it's still not making good boost, then try to find somebody in your area w/a Greddy who will swap actuators with you. Just meet at somebody's house, make the swap, both cars go for a drive, and verify... then swap back of course.

I just saw that you live in Ireland... might be a little tougher.
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Old 08-27-2007, 09:12 AM   #5
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either a boost leak before the turbo (ie., head/manifold or manifold/turbo), or a leak between the throttle body and turbo.

even if the wastegate actuator's diaphram was shot, you'd still get the same spoolup with no limit to the boost as the rod will still be tight holding the wastegate closed....so unless you can easily move the rod with your hand, then I'd rule that out now.
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Old 08-27-2007, 10:05 AM   #6
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Yeah I think I'll put everything back on and do a check again.
I did a quick check on the actuator just by pulling the rob a small bit and there seems to be pressure there so it's possibly ok.
I took off the mani while I was at it and it's perfect
I'll have to get that bit of bolt out of the turbo housing first (downpipe side) and get a replacement.
Thanks & I'll keep you updated.
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Old 08-27-2007, 08:07 PM   #7
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Update:
The bolt that sheered off turned out to be a bit more of a problem than I thought. I've taken care of bolts like this lots of times before on other things without probs but for some reason the bolt is VERY soft metal and was a BiTcH to get out. Also, I used a drill bit that decided to SNAP inside the damn thing so had to drill that sucker out as well.
I used upgraded bolts when I installed it first day and the rest of them are perfect. The hassle bolt is the one that is on the Turbo exhaust side to the downpipe, the highest bolt when it's all together.....I wonder if it's a know problem bolt.
I was very surprised at the condition of all the gaskets ! They are so good I'm using them again.
I managed to get the bolt out anyway and put the T back on the downpipe, mani is back on the car and tomorrow have to 'join' them up which from what I remember is a PAIN to do.
Perhaps time to get another mani & downpipe ?
The Greddy kit is fine but to get at all the bolts when it's on the car is bloody horrible !
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Old 08-29-2007, 11:31 AM   #8
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Update:
Drove the car yesterday evening and there was a small bit more boost than before.
Spooling was better also. I soaped it all up just now and found a leak at the injector mani, even without hitting boost it was bubbling like a blonde on coke :gay:
Gonna fix that by putting a lip of JB weld all around the end of the injector intake pipe so the hose will grip it better.
Sorted soon I hope......
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Old 08-29-2007, 11:31 AM   #9
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Quote:
Originally Posted by Fergus View Post
(PS) There are NO leaks BTW !
DoH!!
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Old 08-29-2007, 02:12 PM   #10
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Quote:
Originally Posted by Fergus View Post
DoH!!
No visable leaks that is. I knew you would find a leak somewhere. There may be more. For you to drop Boost that much, there may be a BIG one that you don't see unless you stand in front of your car with the engine running and jack the throttle up to 4 - 5 K RPM's and let off of it quick - You may see it or you may hear it..
Good Luck on the search,
LOLA
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Old 08-29-2007, 05:37 PM   #11
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Thanks Lola !
I went for a spin (to work - night shift AGH!) and found the boost is back up to about 4.5-5PSI so there is still a leak somewhere.
I'll hunt it down eventually.
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Old 09-14-2007, 11:27 AM   #12
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Update: Boost went back down again.
Decided to change all the piping & couplers etc and get new ones from WOT.
While checking the pipe sizes I found a 1" crack in the silicone coupler on the Turbo outlet, it was just under/beside the clamp hense I didn't spot it before :(
Gonna be sorted soon and back up to 6PSI again !!
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Old 09-14-2007, 05:19 PM   #13
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Hopefully that is.
I had a crack like that in the second coupling after the turbo, and boost stayed the same. I dunno why.
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Old 09-14-2007, 07:41 PM   #14
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I can actually see inside the coupler though so that can't be good LOL
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Old 09-14-2007, 07:52 PM   #15
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That bolt that sheered off, did you by chance try to take it all the way out before you unbolted the rest?

I was talking with my friend while I was pulling it out and stupidly wasn't paying attention, and it sheered off inside the turbo housing. This was a grade 10 bolt, not the normal Greddy ones.

It's good you found the leak.
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Old 09-14-2007, 08:54 PM   #16
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Fergus, u using the stock crossover pipe from turbo to intake manifold?

Steve
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Old 09-14-2007, 10:07 PM   #17
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Quote:
Originally Posted by Stevo11 View Post
Fergus, u using the stock crossover pipe from turbo to intake manifold?
Steve
Yes but I'm getting some parts from WOT to sort that out now.
Dumping all the stock stuff.
It will tie me over until I can get a new Rad (Honda) & IC etc.
I was gonna get them months ago but it's worked out I can only get em now near December.
Ah well, back to 6PSI for a few months is still fun !
Fergus.
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Old 09-14-2007, 10:09 PM   #18
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Quote:
Originally Posted by miataspeed1point6 View Post
That bolt that sheered off, did you by chance try to take it all the way out before you unbolted the rest?
I was talking with my friend while I was pulling it out and stupidly wasn't paying attention, and it sheered off inside the turbo housing. This was a grade 10 bolt, not the normal Greddy ones.
It's good you found the leak.
Yup, that's what happened alright.
I got upgraded bolts as well but it made no difference.
I've drilled it out and put in another one etc.
Fergus.
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Old 10-12-2007, 09:45 AM   #19
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Another update:
I've installed my new pipes and took it for a run late last night.
The Turbo is now clocked downwards into a 3" steel elbow, that then goes into a 3" pipe across in front of the engine up into the TB. AFM is mounted directly on the Turbo.
The car was sitting for about a week as I also was installing a new Greddy kit in a Buddys car and fixing his exhaust.
Went out in the car for a quick test run late last night. What I was doing was bring the car up to 3,000 RPM in 3rd gear and then flooring it. Boost was cutting in at about 3,900 RPM.
I had one of those Bonsi (?) air filters on it and it felt like it was struggling for air. I went home and changed the filter to a K&N 5111. Went out again and boost was cutting in at about 3,700-3,800 RPM. I may try sticking on the Buddys Greddy air filter and see what that does.
It still doesn't feel like it's hitting the full 6PSI though !
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Old 10-12-2007, 10:27 AM   #20
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Any ideas on what to check now guys ?
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