What would cause this???
Melting Slicks
Joined: Dec 2008
Posts: 2,772
Likes: 64
From: Mystic CT
Even if you see it in device manager you may have to manually set itup for the communications settings the software is looking for depending onthe age of the software.If it is looking for a serial port rather than usb it is old or written with older software. Generally Ihave had good luck by forceing the com settings to COM 1 8 bits No parity and 1 stop bit 9600 baud rate as these were the defaults onolder machines. You may ormay not have toplay withinterupt vectors and hardware address as well.
Le Mans Master
Joined: Jul 2007
Posts: 5,043
Likes: 8
From: Tampa Florida
I'm a bit baffled. In the last couple of days my '88 has been exhibiting strange behavior. At idle and the first 25% of gas pedal it seems to run fine, but when I when I put my foot in it, it completely flattens out and won't accelerate at all; even missing a bit. When I let off of the gas, it seems to run OK again. Has anyone else experienced this? I would be very appreciative of any guidance.
It does seem as if you fuel pressure is a bit "low" as compared to a stock 22# setup....but I would think that 30psi with 24#'ers installed wouldn't be low enough to cause a "buck"....maybe a "miss" though.
With the symptoms your describing - my guess - would be an issue with the MAF related circuit, signal and/or sensor.
Team Owner
Joined: Jan 2003
Posts: 20,322
Likes: 248
From: Summerland B.C. Canada
OK, I bought a fuel pressure tester, connected it, and taped it to the windshield. Idle pressure is right at 38. When I got on it hard it still flattened out and started to miss & buck again, but at no time did the pressure gauge go below 30. With 24# injectors, I would think that this should be enough. When I let off the gas and drive gently, all seems normal. I've been assuming that it is a fuel delivery issue, but maybe it's a spark problem. I couldn't find anything in the FSM that addresses this symptom. Any ideas? This has me stumped.
38 at idle is acceptable, but dropping, instead of increasing under load, is not acceptable.
The FSM has some good info for diagnosing.
http://members.shaw.ca/corvette86/Fu...mDiagnosis.pdf
Team Owner
Joined: Jan 2003
Posts: 20,322
Likes: 248
From: Summerland B.C. Canada
There is a timer, so quickly turning the ignition on and off, will not keeping applying 2 seconds of power to relay. I don't recall how many seconds must pass before the ECM will again energize relay, but it's less than 30.
Thread Starter
Racer
Joined: Nov 2006
Posts: 420
Likes: 0
From: Sierra Madre California
Agent 86, your advice to stay focused on the actual problem was right; I was getting sidetracked on the Turbolink connection stuff.
Here is where I sit now. I replaced the fuel pump and filter. Problem still persists. I replaced both of the MAF relays; problem is still there. Finally, I just disconnected the MAF sensor and the car started to run normally.
When I checked the codes (paperclip method) it was storing 33,34,36 and 54.
After clearing them, it is now showing only 34, with the MAF connected.
Clearly, the MAF appears to be the problem; I'm just a bit embarrassed that I didn't try the "just disconnect it" approach earlier.
Now that I have (hopefully) narrowed it down, I am trying to figure out which MAF sensor to buy. Given my current finances, a new one for $700-$800 is out of the question, so I have to go refurbished. I am trying to find out which rebuilds are Bosch, which have wire burn off capability; apparently ACDelco's do not. Not sure if I should even be concerned about this; I may just end up with the Cardone rebuild at AutoZone for $130. I would welcome advice from those who have been down this road.
My sincere thanks to all of you who have provided guidance with this.
Here is where I sit now. I replaced the fuel pump and filter. Problem still persists. I replaced both of the MAF relays; problem is still there. Finally, I just disconnected the MAF sensor and the car started to run normally.
When I checked the codes (paperclip method) it was storing 33,34,36 and 54.
After clearing them, it is now showing only 34, with the MAF connected.
Clearly, the MAF appears to be the problem; I'm just a bit embarrassed that I didn't try the "just disconnect it" approach earlier.
Now that I have (hopefully) narrowed it down, I am trying to figure out which MAF sensor to buy. Given my current finances, a new one for $700-$800 is out of the question, so I have to go refurbished. I am trying to find out which rebuilds are Bosch, which have wire burn off capability; apparently ACDelco's do not. Not sure if I should even be concerned about this; I may just end up with the Cardone rebuild at AutoZone for $130. I would welcome advice from those who have been down this road.
My sincere thanks to all of you who have provided guidance with this.
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