I've posted this before and I'll try again. Eric sent me a chip where he said he took 5% fuel out at spool up. Still didn't help. I can hold rear brakes to 3000 rpm. I know, someone will tell me to get S-10 wheel cylinders. I do have the longer brake shoes on the rear. Wouldn't 3000 rpm be plenty to build boost? I also turned down the fuel pressure to 32 line on. That didn't help. Should I turn down the FP more? I have a Vigilante converter. I think it is 3000 stall. The tranny guy didn't seem to know much about GN's, but he thought this was a good converter. It has the stock cam shaft if that means anything. Any ideas?
No boost at the line
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well if you have a 3000 stall it will truely stall at 3000 with 0 boost. if you put the stock one in you will stall at 2025 at 0 boost and have 10 psi at 3000. your problem is the motor is building rpm that high and over coming the brakes
So can the S-10 wheel cylinders hold the car beyond 3000 rpm? I've asked this before and nobody replied. It seems everybody knows how much boost they can hold but nobody knows at what RPM they launch at. I've also read that some people get their converters restalled to 2800. Do you think this would help me? Thanks.
I had the stock converter before i moved up to the Vigilante. With the stock converter I wasn't able to do a burnout, let alone get any boost. At least that is what I recall. Was several years ago. At the time I had a TE-60 turbo.
I have the same problem too; I haven't checked RPMs but my engine overcomes the rear brakes before building any boost and makes the front tires "scoot" (my front tires are rather skinny). As of right now I believe my torque convertor and rear brakes are completely stock but real soon I'll be replacing EVERYTHING on the brakes (new hardware, adjusters, long soft shoes, S10 wheel cylinders, aluminum drums, and possibly braided stainless brake lines. I have everything but the braided stainless brake lines). I'll report back once I get a chance to get it done.
GNVYUS 1
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Is the car at 3000 then starting to break the tires loose??
Think of your issue like this, if you had a transbrake you'd start to build boost once the converter hits it's stall at 0 boost, from then on it'll build boost and probably creep the stall up due to the motor now making more torque.
But, until that 0 boost stall is reached and there is a solid load it's not going to build anymore boost.
Most likely as soon as you hit 3000 and 0 or 1psi the brakes are no longer able to hold and hence you lost your load ( on the turbo that is ).
Start here, while in reverse hit the brakes to a complete stop about 5 times ( self adjust the shoes ) then try foot braking it. If it breaks them loose after this it's a wheel cylinder issue.
BTW, Jimmy's Trans installed a Stageright for like $250, I no longer worry about vacuum brakes or rear brakes for launching.
Think of your issue like this, if you had a transbrake you'd start to build boost once the converter hits it's stall at 0 boost, from then on it'll build boost and probably creep the stall up due to the motor now making more torque.
But, until that 0 boost stall is reached and there is a solid load it's not going to build anymore boost.
Most likely as soon as you hit 3000 and 0 or 1psi the brakes are no longer able to hold and hence you lost your load ( on the turbo that is ).
Start here, while in reverse hit the brakes to a complete stop about 5 times ( self adjust the shoes ) then try foot braking it. If it breaks them loose after this it's a wheel cylinder issue.
BTW, Jimmy's Trans installed a Stageright for like $250, I no longer worry about vacuum brakes or rear brakes for launching.
I did the reverse brake adjusting procedure. So that isn't it. I guess I just figured if the wheel cylinders were so important then more people would have them. Then again maybe more people do have them. The previous owner did a lot of upgrades, like turbo, downpipe, intercooler, exhaust, gnx dash, injectors, double pumper, suspension, etc. But I guess he missed the wheel cylinders. My mechanic said it still has the stock wheel cylindersIs the car at 3000 then starting to break the tires loose??
Think of your issue like this, if you had a transbrake you'd start to build boost once the converter hits it's stall at 0 boost, from then on it'll build boost and probably creep the stall up due to the motor now making more torque.
But, until that 0 boost stall is reached and there is a solid load it's not going to build anymore boost.
Most likely as soon as you hit 3000 and 0 or 1psi the brakes are no longer able to hold and hence you lost your load ( on the turbo that is ).
Start here, while in reverse hit the brakes to a complete stop about 5 times ( self adjust the shoes ) then try foot braking it. If it breaks them loose after this it's a wheel cylinder issue.
BTW, Jimmy's Trans installed a Stageright for like $250, I no longer worry about vacuum brakes or rear brakes for launching.
As for Jimmy, I spoke to him once and he seemed to not recommend the trans brake. Too much wear on the transmission I think he said. Looks like i"ll be installing new wheel cylinders. BTW what year S-10 should I ask for? Thanks everyone.I did the reverse brake adjusting procedure. So that isn't it. I guess I just figured if the wheel cylinders were so important then more people would have them. Then again maybe more people do have them. The previous owner did a lot of upgrades, like turbo, downpipe, intercooler, exhaust, gnx dash, injectors, double pumper, suspension, etc. But I guess he missed the wheel cylinders. My mechanic said it still has the stock wheel cylinders
The S10 wheel cylinders are a very popular upgrade for these cars. My car may already have them; it probably doesn't. The previous owner did a few things to the car but skipped some very important things (I had to add the Scanmaster for example). All I know is the brakes aren't quite cutting it so I'm starting fresh with them so I know what I have.
Ask for rear wheel cylinders for an '85 S10 with non-power brakes. The non-power part is very important. $22.58 + tax for both sides at NAPA.
Is there anyway u have an exhaust leak, i had a similar problem, didnt think my exhaust manifold was cracked, and it was. Also, not to sound too butch, but i used to use the parking brake, worth a try one time, could launch at about 14 lbs of boost, and it would obv help hold the brakes longer
Thanks!
I'm still chasing this problem. I installed the S-10 wheel cylinders and can hold the car to 3400 rpm per my scan tool.
I took the car to my mechanic for his opinion. He drove it and pointed something out to me. Boost doesn't start until about 3500 rpm....I had attributed that to turbo lag, but now I know that there is somethng wrong. So turbo works the same, whether power braking or just driving normally. I called Precision and they said that turbo (6157e) should definitely kick in before 3500 rpm, although he couldn't say exactly when. Maybe spring in wastegate is weak? It's the ATR external variety, installed by previous owner in 1995. I'll try tightening the screw to increase boost, being careful not to over boost it. From what I can tell, there is a plate in the wastegate that seals off the pipe, holding the exhaust in and making the turbo spin faster. I guess if that plate is in the downpipe it is called a puck. Not sure what it is called in the wastegate.So if it is not the spring, then maybe the plate is not sealing? Does this sound right? My mechanic said the headers are fine and there is no exhaust leak. He said it would take a big leak to exhibit the symptoms I am seeing. All header bolts are tight.
Rick
I took the car to my mechanic for his opinion. He drove it and pointed something out to me. Boost doesn't start until about 3500 rpm....I had attributed that to turbo lag, but now I know that there is somethng wrong. So turbo works the same, whether power braking or just driving normally. I called Precision and they said that turbo (6157e) should definitely kick in before 3500 rpm, although he couldn't say exactly when. Maybe spring in wastegate is weak? It's the ATR external variety, installed by previous owner in 1995. I'll try tightening the screw to increase boost, being careful not to over boost it. From what I can tell, there is a plate in the wastegate that seals off the pipe, holding the exhaust in and making the turbo spin faster. I guess if that plate is in the downpipe it is called a puck. Not sure what it is called in the wastegate.So if it is not the spring, then maybe the plate is not sealing? Does this sound right? My mechanic said the headers are fine and there is no exhaust leak. He said it would take a big leak to exhibit the symptoms I am seeing. All header bolts are tight.
Rick
Careful about turning that wastegate up...if your boost already gets to the maximum level you & the car want it to be at when you get on it while driving then it's not your problem. The plate you're referring to in the wastegate is a poppet valve, similar to your intake & exhaust valves. What kind of boost controller are you running? Can you post a pic of your setup that clearly shows the routing of the boost controller lines? Make sure you don't have any leaks at the downpipe flange and wastegate inlet flange as well. Do you have Scanmaster numbers to post?
challengermike
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My car has a 6157 turbo on it.I have a 2800-3200 stall in it that only stalls to 2,600.Now with mine i have trouble building more than 5-6 #s of boost at the line with the pedal to the floor at 2,600 rpm with the at 02s at 718.Once you get moving it wont come into full boost untill 3,000-3,200 rpm.Now i did for the fun of it try a 3,800 stall converter in it,and it would stall up to what ever boost i wanted at the line.Of course it was way to much stall for the car.My point is that i think that converter you have sounds perfect for your combo.And even if it is way to much stall it should still spool up.
Just a Six??
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Are you sure you have NO pre turbo exhaust leaks. I had one between turbo to downpipe that I couldnt hear but finally found & it Killed all my spool on the line.
I would also look for leaks in the cold side plumbing. I had a slow spool issue that I chased for quite awhile that turned out to be that.
The car ran and drove great, but when I got on the throttle the boost was slow to come on and the car just didn't feel as fast and it had in the past. I finally found the leak with a smoke machine. One of my intercooler clamps had pinched down on the silicone coupler in such a way as to slice it open. Under boost, the slice would open and vent air.
The thing was, the turbo was moving a ton of air, and I was only seeing 15 PSI boost. IAT was through the roof I'm sure, and the MAF was seeing WAY more air than the engine was seeing, so that's why the car ran poorly at WOT.
The car ran and drove great, but when I got on the throttle the boost was slow to come on and the car just didn't feel as fast and it had in the past. I finally found the leak with a smoke machine. One of my intercooler clamps had pinched down on the silicone coupler in such a way as to slice it open. Under boost, the slice would open and vent air.
The thing was, the turbo was moving a ton of air, and I was only seeing 15 PSI boost. IAT was through the roof I'm sure, and the MAF was seeing WAY more air than the engine was seeing, so that's why the car ran poorly at WOT.
I don't have a boost controller outside of the ATR wastegate. No need for further complications. I don't think there are leaks at the wastegate flanges. My mechanic looked at it and he didn't think it was leaking either. Bolts are tight. As for scan tool numbers: TPS .44 .78 1.00 1.39 1.66 1.97 O2 volts .79 .76 .72 .78 .79 .02 .94
I would think pre turbo is from MAF to turbo. Isn't turbo to downpipe "post turbo"? Downpipe bolts to turbo are tight. Can't see or hear any leaks in MAF pipe to turbo. I have an LT-1 MAF and translator if that makes any difference. The air temp. sensor is stuck in the K&N filter. Could that sensor be bad?
I checked and can't see any problems. My mechanic also checked it.
GNVYUS 1
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Ok so brakes are holding to 3400 and car still isn't building boost?
Well at least you can hold 3400 now so that's a positive.
This all started after you bolted on the new turbo right?
If there are no leaks and the car has a good tune then it HAS to be that wastegate in some way. I personally don't run them on just the spring but if you are getting the right total amount of boost ( say 23psi ) then it's possible it's not sealing well etc.
Try installing a manual controller on it and see what happens, they are like $15 on ebay. Not sure if installing a new spring with the same tension matters that those are like $15.
Actually, wasn't Tial having an issue like this when guys ran leaded fuels? Maybe the ATR has the same issue and you need a different valve.
Well at least you can hold 3400 now so that's a positive.
This all started after you bolted on the new turbo right?
If there are no leaks and the car has a good tune then it HAS to be that wastegate in some way. I personally don't run them on just the spring but if you are getting the right total amount of boost ( say 23psi ) then it's possible it's not sealing well etc.
Try installing a manual controller on it and see what happens, they are like $15 on ebay. Not sure if installing a new spring with the same tension matters that those are like $15.
Actually, wasn't Tial having an issue like this when guys ran leaded fuels? Maybe the ATR has the same issue and you need a different valve.
Pre turbo is the exhaust before the turbo, as in the headers, crossover, and turbo to header sealing. Either your gate isn't fully closed, or there's an exhaust leak. Probably the normal crack between the #3 and #5 tubes on the driver's side header. You may not hear the leak, but it does not mean it's not leaking.
Someone suggested that maybe I was too rich...he recommended that I turn down FP to 32. I tried it and it seemed to help at first. I have since returned it to 42.
Happend with old turbo, too.
I have ATR headers. I don't think they were known to crack, but I will check them. Thanks.
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