Need Help with a hot air

[72firebird]

well a friend of mine has a repair shop and a guy just brought in a 84/85 GN and said it stumbles, that he just bought it, and doesn't know whats wrong with it. I guess the guy sold it to him because he couldn't figure out the problem. I don't have any real hot air experience so I thought I would ask about the opinion of those on TB. On to the problem.

The car runs great when parked and you can rev it all you want and it runs smooth. However when you take it out it gets to about 6 psi (really hauls ass up to it and starts destroying the tires) and then it just seems like it dies. The boost will still increase up to 15 psi but obviously the performance isn't there.

The mods on the car from what I could see are K&N, turboxs boost controller, MSD wires, SMC Alcohol injection V2.0, ATR exhaust and downpipe, fuel pump hotwire kit, AC delete, and a Turbo Tweak chip in a 86/87 computer. It says on the ordering instructions that it is a chip made for a 84/85 with a 86/87 computer so I don't think that's the problem. I think it might be the fuel pump because I can't find any papers that have information on him ordering a fuel pump just the hot wire kit. The fuel pressure is around 45 psi at idle with the line off. The motor and tranny supposidley only have about 2k miles on it. The tranny shift really good and the motor seems to be solid. The Turbo Tweak chip is suppose to be made for 22degrees timing in 1st/2nd and 20degrees in 3rd/4th for 20-21 psi.

Right now there is now alcohol in the tank but we'll be adding some tomorrow. I'll also be taking my turbolink over there to help diagnose the problem. I was just wondering if there are any common problems like the fuel pump that I should look at. If you have any questions I will try to answer them the best I can and any help is greatly appreciated.

 

[SLOW_85]

The turbo-link info would be a big step.
Could be alot of things, coil/ignition, plug wires, bad O2 sensor, bad sensor(s).
Could be too much alky bogging the motor down.
Might be a fuel problem.
Some scan data should point you in the right direction.

 

[72firebird]

The turbo-link info would be a big step.
Could be alot of things, coil/ignition, plug wires, bad O2 sensor, bad sensor(s).
Could be too much alky bogging the motor down.
Might be a fuel problem.
Some scan data should point you in the right direction.

well he used his Snap On scan tool and it's not the O2. Currently there isn't any alky in the bottle so that wouldn't be the problem either. I thought that it might be a coil too, is the one off my TTA compatible with the hotairs? The wires look brand new. It said on the chip order that it has 28# stock injectors.

 

[SLOW_85]

The 87 coil will work. The ignition module requires an adapter.
Could be the fuel pump, bad maf sensor.
Plug wires on the passenger side take alot of heat and can look good.
What plug's he running and gap?
Also the timing in the chip is close to stock without the alky.

 

[72firebird]

The 87 coil will work. The ignition module requires an adapter.
Could be the fuel pump, bad maf sensor.
Plug wires on the passenger side take alot of heat and can look good.
What plug's he running and gap?
Also the timing in the chip is close to stock without the alky.

Oh I forgot to mention the turbo said Garret M10 on it. It looked like the stock turbo, but what was the stock boost on the hotairs? I'm not sure what plugs he just put in or at what gap but it had NGKs in it before and was still having the problem. unsure of the plug gap but it really doesn't seem like a spark blow out problem since it continues to build boost. The SES light isn't on so I would guess it shouldn't be the MAF but of course I'll be checking that tomorrow with the Turbolink. The plug wires running to the passenger side have a heat resisting material on them in the are where they run under the piping.

I'm leaning more towards it pulling timing because there's too much boost and not enough fuel. So I think it probably has something to do with it not having any alky in the tank or the fuel pump going out.

 

[SLOW_85]

Oh I forgot to mention the turbo said Garret M10 on it. It looked like the stock turbo, but what was the stock boost on the hotairs? I'm not sure what plugs he just put in or at what gap but it had NGKs in it before and was still having the problem. unsure of the plug gap but it really doesn't seem like a spark blow out problem since it continues to build boost. The SES light isn't on so I would guess it shouldn't be the MAF but of course I'll be checking that tomorrow with the Turbolink. The plug wires running to the passenger side have a heat resisting material on them in the are where they run under the piping.

I'm leaning more towards it pulling timing because there's too much boost and not enough fuel. So I think it probably has something to do with it not having any alky in the tank or the fuel pump going out.

Stock boost was around 10-12 #'s. Sounds like a stock turbo.
Sounds like your on the right track.

 

[boostmaster]

First thing lower your fuel pressure to about 37-40 psi static (line off). 45 psi is way to much to be running on stock boost, rich mixture could cause stumble. Also check you TPS setting should be between .37 - .42 vlts @ idle.

 

[72firebird]

Alright I got the chance to scan it today and there seems to be a lot of problems. I hope this helps with diagnosis.

MAF- stays at 79gm/sec
O2 - stays at 762mV
BLM - around the 150s
IAC - 0-50
Sprak Rtd - this is the kicker, it's about 10 or 11 degrees AT IDLE and up to like 60 degrees when you get on it

At first I was thinking the timing might be off. Looks like the O2 and MAF might be bad but I'm not sure. It's not throwing any codes which I found odd. Anybody have any good ideas?

 

[Tampa T-Type]

Running lean

Your Blm's are way up there, indacates a vacume leak. Did you reset the ecm?
Check all your hoses or plug up all hoses at the vacume block and see what the blm's look like reset the Ecm each time. Do a propane sniffer test on the Egr and Intake.

 

[SLOW_85]

Alright I got the chance to scan it today and there seems to be a lot of problems. I hope this helps with diagnosis.

MAF- stays at 79gm/sec
O2 - stays at 762mV
BLM - around the 150s
IAC - 0-50
Sprak Rtd - this is the kicker, it's about 10 or 11 degrees AT IDLE and up to like 60 degrees when you get on it

At first I was thinking the timing might be off. Looks like the O2 and MAF might be bad but I'm not sure. It's not throwing any codes which I found odd. Anybody have any good ideas?

Yeah, outta wack. The maf readings should go up under load.
O2's should be moving,changing constantly. Prolly fouled out.
BLM's showing it's trying to lean the car out.
As suggested to high a fuel pressure probably.
If it's really knocking that bad, you should be able to hear it.
Sounds like it's going to take some work to get running right.
Is it a 87 maf? Aftermarket boost gauge?
TPS reading? Octane your running? Exhaust leak(s)? Voltage readings?


Here's the quick reference off gnttype:
http://www.gnttype.org/maint/quickref.html

On my page there's some vacuum diagrams might want to check out the lines.
http://www.geocities.com/gnowner85/info.html

 

[boosted84]

The fact that the chip has more timing because its made to run with alky and because there is no alky being used there is too much timing. Put some alky in and see what happens and also I would see about monitoring knock

 

[72firebird]

The fact that the chip has more timing because its made to run with alky and because there is no alky being used there is too much timing. Put some alky in and see what happens and also I would see about monitoring knock

alky doesn't spray at idle so it's not going to solve the 11 degrees or so that its retarding at idle. I think the knock sensor might be bad but I didn't think it would continually retard timing if it wasn't working correctly.

Slow_85 - this is a aftermarket boost guage that I'm using. My scan tool wasn't giving me a TPS reading so I'll have to do it manually tomorrow. I didn't get the chance to lower the fuel pressure, but the paper work for the chip says to run the car at 43 psi I believe for fuel pressure. The car is running rich as hell, you can see it coming out the exhaust and after removing the plugs they were practically solid black. I think the MAF was a 87 but I don't know how to tell the difference (it looked like an 87). I'll try taking mine over there and hooking it up and seeing if it helps. After looking at Advance Auto Parts online it looks like the 84 O2 sensor is the same as my TTA so I have an extra one sitting around that I'll try hooking up too. There's no exhaust leaks that I noticed anywhere.

You can't really hear the knock. It just sounds like loss of power, or maybe like downshifting so you have high rpms but no boost but a little quieter. There's no ping noise or anything, and at 60deg of timing retard it should be fairly loud I would think, or actually probably I don't think the motor would live through it.

 

[boosted84]

sorry forgot it was at idle stupid reply on my part in the begining you said there was only about 2000 miles on it and i remember reading that there are after market lifters thats cause false knock at idle and on in that power pac book it says rhoads or crane lifters can cause the detonation sensor to pull back timing resulting in surging maybe the guy who rebuilt it put them in. Any noise at all from egnine like dp hitting heater box or anything just tryin to think of what could cause this its very odd


Ps To tell the difference between the maf the 86/87 plug is usually level and the 84/85 is under the square portion of the sensor pointing down usually

Anthony

 

[SLOW_85]

That's why I asked if you could hear anything.
Might be false knock, sensor hearing something in the motor,etc.
Knock sensor may be over torqued (should be 14 ft/lbs).
I'd try the 87 maf, O2 sensor maybe ohm out the plug wires, coil.
Change plugs, gap @ .035.
TPS may be way off.
All the sensor have to be good, so the ecm can control fueling from the input.
Also what's the motor temp? Coolant sensor is important too.

 

[turbofish38]

Ps To tell the difference between the maf the 86/87 plug is usually level and the 84/85 is under the square portion of the sensor pointing down usually

Not all of the 86-87 MAF's are like that. The easiest way to tell is the 84-85 MAF has 4 screws holding down the cover and are visible from the top. The 86-87 has no screws and is usually glued or bonded together. Also there may be a paper label on the bottom side by the plug. 25007699 is the 84-85 number and 25007866/25007861 are the 86-87 numbers. Aftermarket sensors usually use the last 4 digits of the GM part numbers.

 

[72firebird]

Well it had an 87 MAF on it so I swaped mine in and it still didn't read. I swapped in my O2 and it didn't work either. So I'm starting to think it might be the computer. When you start the car it sounds like it's sucking a lot of air through the filter. It's so loud that it almost sounds like a belt screech. It lasts a couple minutes and once it warms up it goes away. I think the ugy is going to be taking it to one of the local GN guys to work on. I wouldn't mind figuring it out but I don't want to put hours and hours into so my friend's dad can get money for fixing it and probably not pay me. So I was just trying to help the ugy out and diagnose it some. I think the car really has a lot of problems.

For swapping to an 87 computer do you have to do anything besides for change the wiring on the MAF? It looked like he had one wire that was running to one of the pins for the computer that wasn't stock and that was the only thing that was changed on the computer end from what I can tell.

 

[SLOW_85]

The 87 ecm should plug right in. The wire should be for a mat sensor, needed to be added. Sensor and wire to the 87 ecm. There should be no extra wire from the maf sensor it self.

http://www.gnttype.org/techarea/ecmsensors/8487ecm.html