4agze Nevo 175mm only 9psi, is belt slipping?

[dave_101]

Hey everyone,

Just wanted to get some advice before I take my corolla to the mechanics for a check up. I am not a mechanic, so please excuse my ignorance in some basic areas.

She has a AE101 4agze with the Nevo 175mm pulley & FMIC running 2.25" pipe, before the FMIC she was getting just on 15psi, after FMIC about 13psi in most gears, think the big drop was due to the larger than 2" pipe and massive IC they put in. Recently though I have noticed a decent drop in the pressure, it's most noticeable in first or second gear, seems to only hit 9psi and 10psi at the most, 3rd gear seems to do 10psi no problem and even push to 11psi, but before 3rd would be 13psi to 14psi no problem.

Also notice in second it can go up to 10psi at say 4000rpm, but just after I see it drop quickly to 9psi.

Does this sound like the belt is slipping maybe? since there is a lot more toque going on in 1st and 2nd gear and not so much in 3rd which maybe why it seems better in 3rd. Or is there may be a leak in the IC pipes or seals?

Something else I took a look into today was the ABV mod, just wanted to check the hose coming off the throttle body was still blocked off, checked that out and it was, but then took a look at the ABV itself and there was no hoses connected to it at all, from what I read I thought it was meant to be connected to the manifold where the boost gauge currently is, so I went ahead and did that, no change. Just so I know, the way it was with no hoses connected to it all, was that bad?

Thanks in advance for anyone that can reply, just want to try and work out what might be causing the drop in boost, also would love to know if the ABV not having any hoses hooked up was wrong or not.

Dave

[slide86]

my mate had a GZE in an ae92 with the same pulley and cooler setup you did.

we had a hell of a time trying to get the belt tight, but he also noticed the boost drop which was caused by a loose belt.

even though the belt felt tight it was actually still loose enough to cause some slip. you really need to crank on the tensioner to get it tight enough.

after we got it super tight, it was seeing 14psi everyday of the week.

look into that ABV too, that will definitely have an affect on boost levels

[TERRA Operative]

Plumb the ABV into the pipe coming out of the supercharger. It's a better version of the traditional ABV mod.

http://www.jdmlevin.com/files/NewABVMod.pdf


Also, make sure your belts are tightened to factory spec or tighter.




Lastly, check you have no more than 0.65mm clearance between the clutch plate and the pulley when the supercharger is disengaged. The factory spec is 0.35 to 0.65mm any more and your clutch will slip.
To bring the clearance down, you have to remove the clutch (just a nut and maybe a few screws) and there is a washer inside, just file it down until you have the correct clearance when it's assembled.
(Toyota did supply different thicknesses, but not anymore).

[dave_101]

Hey thanks for the fast replies guys.

slide86, yeah I think the first thing im going to get my guy to check is the belt, as it has been taken off 6-months ago when I had the SC12's clutch replaced becasue it died, maybe the belt was not put back on tight enough, what were your mates typical symptoms of belt slip? Did he see random drops of boost & at certain RPM or gears?

I don't really see big drops in boost, and its not really random either, shes fairly consistent, the most she seems to drop is about 1psi, it does happen all of a sudden though, the real weird thing is the fact 1st and 2nd gear rarely go over 9psi now, has no problem getting there, just once she does which is pretty low in the RPM, I get nothing more unless I go into 3rd and then I can get may be another 1psi.

TERRA Operative, thanks for the detailed reply as well mate, funny you mention that newer ABV mod, I found it today while looking up the first version of the mod to check if something had gone wrong with it. I am kinda worried to why the ABV has not been connected to anything, if it's got nothing connected wouldnt it be in a permenent state of open? While reading today I saw some people remove them completely and plug up the hole, is that not advised or would it be safe to do just to test out if the ABV is adding to the problem?

From what I can tell the ABV has been disconnected from the begining and she was making plenty of boost before, I did look today to see if any pipes had fallen off the ABV and could not see anything, so I have to assume it was like that all the time, hooking it up to the manifold today made no difference at all.

Really glad you brought up the SC12's clutch as well, something I had not thought of and I had to get the clutch in the SC12 replaced about 6-months ago, funnily enough and thinking about it now that is around the time the trouble started, so I am tending to lean towards the clutch or the belt as both were played with when the clutch was replaced. Are there any typical signs that the clutch is slipping, is it more likely to slip under high torque like 1st and 2nd gear give?

I do seem to have a pretty consistent loss of boost all round, would that be the case if the clutch was not done right?

Thanks again for the replies guys.

[TERRA Operative]

You can remove the ABV, but it's not recommended as the air can't flow through the supercharger very easily so you will be engine braking quite a bit during deceleration, making it somewhat jerky at small throttle inputs.

A slipping clutch will present like a slipping belt. Boost to a certain point then slip so the boost won't build any more.
In both cases it's most likely to slip at higher boost as that's when the most resistance is generated. (Ie. the SC14 requires 12kW to spin at full boost)

The ABV is normally closed, opening when vacuum is present at the small vac port, or when the boost level overcomes the spring pressure in the ABV.
Presenting boost to the vac port will hold the valve closed, and plumbing it to the supercharger as linked above will present a higher level of boost than from the manifold (boost drop from the intercooler etc) and close the ABV faster (boost lag from the long intake tract).

You can test out not using the ABV by cutting a bit of coke can in the shape of the gasket and slipping it between the ABV and where it bolts to the manifold.

[dave_101]

It's starting to sound more and more like the new clutch that was put in the SC is the problem, pretty much what you describe is what I am getting, after doing a little more reading some say when the belt slips you can kinda hear it, I don't hear anything out of the ordinary at all, and since the clutch was re-done, I am starting to think it's the problem.

Thanks for the tip with the ABV, that's something I can try myself before I take her in.

Hey I might as well ask since I noticed you are in QLD as well, my normal mechanic I think is a little over working on the old GZE's, he seems to do a lot more with those 2JZ-GTE, do you happen to do work on cars for people, or know of someone in the Brisbane area that knows GZE's really well?

Really happy with my normal mechanic, but he tends to be quite busy as well and it might be hard to get him to take a good look for me, so if you are in Brisy or know a good place would love to know.

[TERRA Operative]

Yea, if you can get your car to Runcorn (just south of Sunnybank Hills), I'll be happy to look at it on a weekend. I kinda know the GZE inside out...

(I'm currently rebuilding an SC14 for my GZE).

[dave_101]

Thanks a lot mate, I am only a 20min drive tops from Runcorn, am over in Carina, really want someone looking at her that really knows the motor and the SC. Shes a really nice motor, everything is stock and after I had the FMIC installed it was running 122kwatw, want to get her back to that.

Maybe PM me your details or if you want I can PM you mine, would not mind having a quick chat on the phone just to work out what time is good for you etc.

[TERRA Operative]

PM'd you details.