I just installed the TopGun160 and associated filters, etc. and the car launches like a rocket booster! :D
The problem, though, is that when it gets to moderate RPM and toward full boost, it lays down and dogs :( , very little power, and actually starts to surge as if fuel delivery is being interrupted. I believe there is a chip function that senses overboost and cuts fuel to prevent damage, but my concern is what is allowing overboost.
I am not as experienced as many of the rest of the board buddies, so some of you that have been down the road w/ the chip and seen this type of problem might be able to kick-start me toward where to check for the problem. Like how is the correct way to check for proper wastegate opperation, and how do you check the valve in the wastegate pressure control line between the turbo outlet and the wastegate?
Any help appreciated, & I really like the chip, just need to find the other problem so the chip can work the way it is supposed to.
Thanks
not To Sure but it almost sounds like you Fuel pump cant keep up or you have a miss in and injector.
what octaine gas are you using? 91+??
Octane: this tank is 91, it does'nt have any knock/ping identifiable
Had'nt thought about the pump, I have replace the filter very recently, < 500 miles ago, though. Also did a flow test, and did not appear to be a problem then, but the filter could have plugged in the few weeks since it was replaced. Guess I'll need to recheck.
Thanks for the advise, will post results as I get there. Any one else have an idea on this?
You havent said what all you did in the Jeff M fix all packet.
I have done almost everything but put in my Iridium plugs and spiral core wires, and pcv valve, and I got vacuum leaks. My car still surges and cuts but I got it to stop stalling.Let you know when I do this long list of sh@t.
Went looking for this thread because of your last message!
I would check the ignition system if you haven't done so already. Sounds like as the cylinder pressure gets higher the spark isn't keeping up. Had a problem with this a while back, I too thought it was a fuel system problem until I kinda stumbled on the bad wires that I had just replaced not too long ago. I would do a fuel pressure check if you have a guage just to eliminate that possibility. You can tape it to the windsheild and watch what its doing, or just pinch off the return line to see if it can get the pressure up high (should go to around 70). Pressure and flow are related to each other, so if the pump can make the pressure it should be able to make the flow (base fuel pressure is around 40, and as boost rises fuel pressure rises at a 1:1 ratio, so max fuel pressure should be 50-52 psi)
Thanks Chris, for looking for this thread again.
As of the last posting, it gave me an idea. :idea: I had checked the actuator for pressure/vacuum leak, and there was none. I had not checked it for threshold, and that is somewhat difficult to do. What I thought might be a valid test based on discussions I've seen would be to bypass the controll solenoid (the one on the top/front of the engine) connecting the output of the turbo to the actuator directly. My understanding is that the actuator is set for approximately 4 +/- 1/2 # of boost, so I should see the boost top of at 4 # on the dash guage regardless of throttle.
Well, goodness sakes alive, :? this thing according to the dash guage, climbs to ~12 # of boost at mid throttle and above, leading me to believe I have a stiff actuator on the turbo.
So now my question: is this a valid indicator? :?:
BTW, I have pulled the plugs numerous times, started at a gap of .040, then went to .035, now am at .030, each time it improved a little. I thought .035 was spec, the last two times are with R42LTS. Wires are less than 3K miles old, but I know what you say about them being bad after replacement. (I really don't think this is it, though.) Plug color and condition was good when pulled to regap the last time, didn't indicate excessive carbon/fouling, the cavity had slight carbon, but the tip, insulator, and tang were all normal color.
Also, all vacuum lines have been traced and looked over, couldn't find any that were leaking.
Fuel pressure tested ~45 static and peaked somewhere near 70 as I recall, can't remember the exact #'s so I'm going to run that test again to be sure.
Another question, :idea: until I get this solved, is there a real big reason to re-connect the solenoid since this seems to help drivability a little, it doesn't peg the boost now as it did before, and allows the throttle to be opened wider than before before it dogs down. I just want to be sure, as my daughter needs to drive this car since someone ran a stop sign & T-Boned her a week ago and totalled her car. Just want to make sure it is safe to drive, and not going to do something to cause her a problem.
(Wish someone had given me something like a TGP when I was 18!! :!:
No. there is no harm in running it directly to the actuator. The solenoid can only increase boost past the actuators minimum by removing the boost signal to the actuator. The dash guage is highly inaccurate for anything other than showing that there is boost. As far as how much, its very hard to conclude from the dash guage. However, it would be odd to have a heavy actuator, but I suppose its entirely possible. The best thing I could suggest to check that woiuild be a mighty vac, so you can pressureize the actuator and see how it moves and at what pressure. You can also get a pressure guage of some sort and some vacuum hose and tap into the boost line and see what boost you are really running. I was quite surprised the first time I did this.
Even so, if you have the top gun chip, it shouldn't break up unless you are SERIOUSLY overboosting. Jeff has enough safeguard built into the chip that it shouldn't cause a problem. Not sure where to go on this one. Sounds like you've checked the fuel system pressure, inspected the plugs, vacuum hoses etc, recently done wires, possiblility for a weak coil but I highly doubt that. If the fuel pump is making 70 psi then I doubt its weak. Just because of my experience if I had done all those things, and can't find a problem with the actuator, I would go to where I bought the wires and get a replacmenet warranty set and try that just for grins. Sometimes the obviously right can be bad. IE recently, after testing and testing a friends car battery having intermittent trouble cranking over (like spark was way advanced or high compression) discovered the battery is infact weak under load. Hooking a booster pack up fixes the cranking problem immediately and I had disabled the spark so there was no way it was spark advance. Anyway, hope I'm helping some, chronic problems can be so very frustrating.
Chris
You say your running AC Delco plugs? Try getting new plugs, but not AC Delco's. I know you said your plugs are new and not showing any bad signs. I usually run Accels but I wanted to take them to work and clean them so I bought a set of Delco's. I gapped them to .035. My car would barely run. It ran like it had a dead coil. Put the Accels back in and it ran fine. I was told that there was a batch of bad plugs made and I guess I lucked into getting a set of them.
The first set of plugs were champions, ran just as bad!
Also, based on another thread visenus posted, I'm going to try re-plumbing the turbo to wastegate to make sure I don't have a leak, since I'm bypassing it at the solenoid, it may be leaking at the turbo or actuator, it would not open the acutator and allow it to overboost.
Should be real easy, and eliminate all possiblities there. While I'm at it, I am going to T it and put a valve on and some pressure to see exactly where it actuates.
I'll post results, this is getting me excited!
Quote from: corvettethis is getting me excited!
Sounds like me when I try new stuff on my car.
Quote from: corvetteAnother question, :idea: until I get this solved, is there a real big reason to re-connect the solenoid since this seems to help drivability a little, !:
Oh, maybe I read wrong. Did you unplug the electrical connector or bypass it by re routing the vacuum lines?
I didn't read previous post, but i woud suspect ignition coil /wires if you have not already changed, them. I battled a miss/cutout under boost, changes plugs helped for a little while, it got worse and was missing at idle, hooked timing light up and saw misses, you should be able hook timing light and run inside care and look for loss of spark.
ChrisA, I bypassed the air line around the solenoid, at the solenoid. Have not had time to re-plumb it, I'm goning to try a fresh line directly from the turbo to the wastegate w/ some small spring clamps to be sure. I'll let you know the results.
While I wait, in anticipation of need one, any one have a known good wastegate. Suspect that is what I'm going to find is the problem, taking 7-8 pounds instead of the normal 4-4&12 pounds I belive to be spec.
PM me if you know where a good one is. Thanks.
I finally found :D the problem of overboost I have been chasing for months!
My find is that there is a hairline crack in the line from the turbo to the ecm-turbo-control-solenoid which was bleeding about (in my estimation) 7 to 8 #'s of pressure from the wastegate actuator, thereby allowing for early overboost.
Now the interesting :? part, in my troubleshooting I made sure I had very firm connections to the solenoid, turbo, and wastegate actuator, but when I bypassed the solenoid to go to minimum boost (should have been < 5 #'s) I had nearly a full gauge of boost at only mid throttle. My bypass was at the solenoid end of the lines, cause the lines appeared good when I reworked the turbo and the connections were firm cause I rechecked them a couple times.
Any way, as a trigger from all your help, one of the chaps with a similar problem found a leaking connection to the turbo or actuator (cracked from heat) so I thought, I'm going to eliminate all doubts and determine if it is the actuator or what so I put a brand new hose on the turbo to actuator, less than a foot long, and what did I get? You guessed it! About 33% of a gauge of boost at any throttle and a very happy engine. :fadein:
I did not have enough time to re-plumb the line with new hard line, but will get to it tomorrow, daughter needed the car before I had enough time to finish.
Any way, thanks to all of those who have tried to offer suggestions and hep, it was all appreciated. Now for getting on with the rest of the project, making this the tire smokin' spoolin' and crusin' machine it really can be!
It now can wear it's name proudly, cause 'Spanky' will be spankin' those fart-can-mobiles in style! :!: