Major Problem Please Help... 1G GSX

[GSXlaunch]

For over a month I have been having a problem with my 90 gsx going full lean. So bad it is not driveable. Ever since the Magnus Intake install it has been nothing but problems. When I first go to start it up it starts up fine...idles great, trims are good (on the rich side). Once it warms up, it goes full lean. I can hear the idle change as it goes lean. It starts to miss a little and I am afraid to keep it running for more then a few minutes at a time with out it cooling down. Again, once it is warming up, the o2 seems to cycle fine. Once it warms up, o2 trims are at 180-199% and o2 voltage is at .02 and stays there. Things I have checked and or replaced:

Fuel pump oring (checked)
Fuel pump strainer (changed)
Have a hot wire right to the pump
Voltage to the pump is 14
Fuel filter changed
changed to afpr (set at 38)
no leaks present at injector seals
checked for boost leaks via the carb spray method
drained tank and replaced with 93 octane

I dont know where to go next. This is driving me crazy. Does this sound like an o2 sensor that is failing? If so, I will buy a new one tomorrow. I am desperate people. Any and all help is greatly appreciated.

 

[andymoraitis]

I got to the end of your post and thought "has he checked the O2 yet?" I would certainly replace that next since it can cause the strange behavior you're having.

Let us know what happens,

Andy

 

[GSXlaunch]

True. I have been trying to find a donor to test and have been unsuccessful. I called up Mistu and found one for 90 bucks. Advance Auto wanted $118!!! She better put out big time once this gets resolved. I will post after the new o2 sensor is installed. Thanks by the way.

 

[GSXlaunch]

Another thing I forgot to mention is that I changed from a non-eprom to Eprom ECU and still the same problem. I get no CELs or errors according to the logger. I'm stumped...hopefully its the o2 sensor.

 

[GSXlaunch]

Well, tried a freinds o2 sensor...no change. Actually, o2 trims did not do much of anything and stayed at 100%. O2 voltage hovered between .10 and .12. I changed all the settings on my translator to "0" and swapped my denso o2 back in. l also checked my plugs and they all looked normal...the electrode tip looked a little whitish but nothing to out of the ordinary. I did notice that two of my plugs were incorrectly gapped at .15. I changed that as well. The car seemed a little better but now it is running rich...full rich. At idle, it is still full lean. Very freaky. I drove it about a mile...I tried to get on boost and it seemed to sputter severly so I laid off. On the way back home it really did not want to idle and shut off few times but fired up right away. I am fresh out of ideas...

 

[Newlogics]

Well, to get the basics out of the way, check base timing at adjust in needed.
How much do you trust your injectors? What's injector duty cycle/pulse width?
Does it change drastically after it warms up? (This will help you figure out if the problem is with sensor readouts or fuel delivery system)

Are there any abnormalities in MAF readings?

 

[GSXlaunch]

I did do a quick log when trying to get on boost but I left me logger at home so I cant post the results. I did notice on the way to the house that my o2 trims were in the 20% range and actually dropped to zero. I even saw my o2 voltage jump to 4.82 volts?????? So now its full rich when driving...at idle full lean (199% o2 trims and .02 volts). All i did was zero out the maft so I can do my adjusting/testing with the safc. I did notice o2 volts cycling normally tho between .2 and .9 when cruising. I had zero knock, the car is not smoking at all. My timing is at about 5. Injector duty cycle never went past 42%.

 

[Blurple90]

I'm having a similar problem. what kind of fpr are you using and what is it set at?

 

[GSXlaunch]

aeromotive set at 38psi. I did switch back to my stocker just to see what it would do and it did the same thing. I did notice that pressure would drop to 0 on the afpr with in ten seconds once the ignition was turned off. I have it at a local dsm shop. Unfortunately, they seemed baffled by my cars behavior as well.

Edit...with my wife following me to the shop. She told me that she could see dark or grayish smoke coming from the tail pipe when I would shift and when I would get on the slightest boost. However, when I would come to a stop, it would go full lean and would want to shut off. When cruising, my o2 trims were at 20% and sometimes would fluctuate between 0% and 15%. Something is seriously wrong....!!!!!!!!!!

 

[Newlogics]

aeromotive set at 38psi. I did switch back to my stocker just to see what it would do and it did the same thing. I did notice that pressure would drop to 0 on the afpr with in ten seconds once the ignition was turned off. I have it at a local dsm shop. Unfortunately, they seemed baffled by my cars behavior as well.

Edit...with my wife following me to the shop. She told me that she could see dark or grayish smoke coming from the tail pipe when I would shift and when I would get on the slightest boost. However, when I would come to a stop, it would go full lean and would want to shut off. When cruising, my o2 trims were at 20% and sometimes would fluctuate between 0% and 15%. Something is seriously wrong....!!!!!!!!!!

Try borrowing an ECU form someone to see if it helps and makes any difference. Far cry, but I can't think of another single thing to cause those simptoms.

 

[Newlogics]

Try borrowing an ECU form someone to see if it helps and makes any difference. Far cry, but I can't think of another single thing to cause those simptoms.

Also, log the car and see if your airflow readings roughly correspond to speed/rpm/load.

 

[GSXlaunch]

I have a new rebuilt eprom ecu installed...same symptoms as before. As for airflow, the last time I logged it, it seemed to be okay. Things I have not checked...injectors, gm mass. The gm mass has no screen. I doubt this will make any difference but thought i'd mention it. Again, this all started after the magnus install. Would a bad ground cause this? How important is it for the power transitor and coil pack to be grounded? It would be such a dam shame to part the car out because of this mess. It ran pretty strong before the intake install....just another reason to let well enough alone. This is really screwing me up....! Ideas are tremendously appreciated.

 

[GSXlaunch]

Well finally broke down and took the car in to a dsm shop. They guy up there has been working on dsm's for many years and really knows his stuff. I trust what he says. He seems to think it is a simple tuning issue but I feel he may think otherwise once he drives the car. Eitherway, the only thing I was concerned with was the fact that he thought that bumping the timing up to 17 would help. Someone correct me if I am wrong but I thought these cars should be at 5 and then left alone. He also suggested bumping base pressure on the 45-50. Again, I trust what he says but was only concerned abou these things. I figured I'd double check with you guys first before I brought it up to him and made an ass of myself. Thanks

 

[Newlogics]

Well finally broke down and took the car in to a dsm shop. They guy up there has been working on dsm's for many years and really knows his stuff. I trust what he says. He seems to think it is a simple tuning issue but I feel he may think otherwise once he drives the car. Eitherway, the only thing I was concerned with was the fact that he thought that bumping the timing up to 17 would help. Someone correct me if I am wrong but I thought these cars should be at 5 and then left alone. He also suggested bumping base pressure on the 45-50. Again, I trust what he says but was only concerned abou these things. I figured I'd double check with you guys first before I brought it up to him and made an ass of myself. Thanks

Even if those things he suggested (which are rather radical) do help, it will only be a patchwork. You need to get down to the cause. What T/B are you using with that manifold?
What injectors?

 

[GSXlaunch]

75#/hr or 780cc injectors with a high flow walbro 255 pump. I have the stock tb mounted to the magnus. Supposedly he was going to get a wide band hooked up (if he was able to find bung and put a secondary hole in the o2 housing). I thought that advancing timing = a leaner mixture....problem with mine is that sometimes it is full lean and sometimes its full rich. It will not build boost past 5lbs before it starts to sputter drastically; almost like a mini-fuel cut.

 

[Newlogics]

75#/hr or 780cc injectors with a high flow walbro 255 pump. I have the stock tb mounted to the magnus. Supposedly he was going to get a wide band hooked up (if he was able to find bung and put a secondary hole in the o2 housing). I thought that advancing timing = a leaner mixture....problem with mine is that sometimes it is full lean and sometimes its full rich. It will not build boost past 5lbs before it starts to sputter drastically; almost like a mini-fuel cut.

This may sound rather simple, but check idle switch wire and make sure it's on and making good contact. Make sure your idle switch works (via logger). Also go over idle control motor plug and make sure wires aren't damaged and plug is snug. If idle switch is 'stuck' off, the motor is running constantly in deceleration mode. (Note that idle switch reading is 'off' at idle and 'on' off idle)

When runing into problems like this, you should first look for causes in places that you have worked on before it happened. (intake mani. area). Go over every connector there. Check all vacuum lines for poper routing (especially FPR vacuum wire, that one should be coming directly from manifold port. Disregard stock solenoid)

 

[GSXlaunch]

By idle switch do you mean TPS?? I hate to sound like an idiot but I am not sure where the idle switch wire is. My TPS does register on the logger...but to be honest it almost does seem like it is running in deceleration mode...very interesting. As for the FPR vacuum it is running directly off the manifold. I discarded the fpr solenoid months ago as I read on taboo's site that is wasnt needed. Keep the ideas coming...those are great. Thanks, by the way for helping me out.

 

[Newlogics]

By idle switch do you mean TPS?? I hate to sound like an idiot but I am not sure where the idle switch is. My TPS does register on the logger...but to be honest it almost does seem like it is running in deceleration mode...very interesting. As for the FPR vacuum it is running directly off the manifold. I discarded the fpr solenoid months ago as I read on taboo's site that is wasnt needed. Keep the ideas coming...those are great. Thanks, by the way for helping me out.

idle switch is that single wire sitting on top of where throttle cable connects with the throttle body (that spring spindle). Basically, there is a small switch sitting there next to that throttle spring. It normally on. When throttle is depressed, it pushes against the switch, turning the switch off. This is how ECU knows if the car is idling or not.

 

[GSXlaunch]

Is that thing there on 90's as well. I dont remember disconnecting/connecting that sucker. I am thinking of driving to the shop and checking it myself.

Edit: I just looked at the hot click diagram for the 1G and saw the idle switch wire. Man, I remember having problems with that bi*** wire snapping off a couple of times since the magnus puts the t-body lower. Dude, if that is it, I'll send you Christmas cards forever.

 

[Newlogics]

Is that thing there on 90's as well. I dont remember disconnecting/connecting that sucker. I am thinking of driving to the shop and checking it myself.

I'll post more later tonight. I have a 90 in my shop, so I'll double check the location.

 

[Newlogics]

here it is ( 90 TB )

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There is one wire going to it.
If it's disconnected, the car will idle surge, have too high of an idle and such.
If that wire is grounded somewhere, however, the car will permanently be in 'idle' mode.

 

[GSXlaunch]

Welp just checked it. I drove the 40 minute round trip just to see for myself. Turns out it was connected and according to my logger the idle switch is working perfectly. CRAP! I thought for sure that would be it. Tomorrow, we are putting a bung for the second o2 sensor for the wide band. THis should tell us what it is really doing. That was a dam good call tho man. That could have easily been it.

 

[BaddAssGst]

Was the car running fine before the Magnus Manifold install? If it ran fine, I would say that your problem lies somewhere in there. Maybe switch it back to the stock manifold and see if the problem continues.

I guess I'm not sure where I'm going with this but figure out the last time your car really ran good and trace back through your steps. Maybe it was something small you missed or didn't do that is causing you all these problems.

 

[GSXlaunch]

It was running fine before the magnus intake manifold install. I wanted to just start over from the beginning. My problem is that I sold my stock manifold. The person at the shop seems to think it is a simple tuning issue and that it will be ready for the track tonight. I dont feel optimisic about it since it has been an issue for almost two months now. He is going to drive it for the first time today and hopefully log with the wideband.... I guess we'll see. I 'll post up the results....thanks again for the help.

 

[BaddAssGst]

Definitely let us know. Hopefully it is just a tuning issue that needs to be fixed. I really think that your problem lies somewhere in the manifold though. It only seems to make sense that after the install is when your problem started. But then again, it doesn't seem like a Magnus manifold would all of the sudden make you start running lean..