Car dies
Thread Starter
8th Gear
Joined: Jan 2019
Posts: 8
Likes: 0
From: Denver
Car dies
Hi guys,
been fighting this fpr a while maybe some suggestions.
New exhaust, injectors, plugs, wires, distributor, maf sensor, TPI, IAC valve
when maf is connected car will idle the second the throttle is cracked car dies. Verified TPI voltage is correct.
when maf is disconnected car runs fine but posts a maf sensor error (not unexpected).
suggestions? Would obviously rather have everything hooked up.
been fighting this fpr a while maybe some suggestions.
New exhaust, injectors, plugs, wires, distributor, maf sensor, TPI, IAC valve
when maf is connected car will idle the second the throttle is cracked car dies. Verified TPI voltage is correct.
when maf is disconnected car runs fine but posts a maf sensor error (not unexpected).
suggestions? Would obviously rather have everything hooked up.
Last edited by Vetteboy31; Jan 25, 2019 at 12:14 AM.
Melting Slicks
Joined: Nov 2007
Posts: 2,830
Likes: 147
From: Gainesville FL
Hi guys,
been fighting this fpr a while maybe some suggestions.
New exhaust, injectors, plugs, wires, distributor, maf sensor, TPI, IAC valve
when maf is connected car will idle the second the throttle is cracked car dies. Verified TPI voltage is correct.
when maf is disconnected car runs fine but posts a maf sensor error (not unexpected).
suggestions? Would obviously rather have everything hooked up.
been fighting this fpr a while maybe some suggestions.
New exhaust, injectors, plugs, wires, distributor, maf sensor, TPI, IAC valve
when maf is connected car will idle the second the throttle is cracked car dies. Verified TPI voltage is correct.
when maf is disconnected car runs fine but posts a maf sensor error (not unexpected).
suggestions? Would obviously rather have everything hooked up.
Good luck
Do you have a factory service manual?
Thread Starter
8th Gear
Joined: Jan 2019
Posts: 8
Likes: 0
From: Denver
I have an FSM but it doesnt talk on this much. I've replaced the pressure regulator to no avail. The way this is acting its seems to be telling me there os something in the electronics going on. Another clue might be that when I put the never versions of the MAF sensor in it still throws a MAF error. The older design MAF won't throw a code but that is when the car starts exhibiting this behavior. Oh yes its an 85
Last edited by Vetteboy31; Jan 25, 2019 at 09:28 AM.
Drifting
Joined: Jun 2018
Posts: 1,678
Likes: 229
From: Michigan
Hi guys,
been fighting this fpr a while maybe some suggestions.
New exhaust, injectors, plugs, wires, distributor, maf sensor, TPI, IAC valve
when maf is connected car will idle the second the throttle is cracked car dies. Verified TPI voltage is correct.
when maf is disconnected car runs fine but posts a maf sensor error (not unexpected).
suggestions? Would obviously rather have everything hooked up.
been fighting this fpr a while maybe some suggestions.
New exhaust, injectors, plugs, wires, distributor, maf sensor, TPI, IAC valve
when maf is connected car will idle the second the throttle is cracked car dies. Verified TPI voltage is correct.
when maf is disconnected car runs fine but posts a maf sensor error (not unexpected).
suggestions? Would obviously rather have everything hooked up.
As far as your MAF goes, there is a lot to check into. You should research getting a scan tool set up. A lot of us use a software, laptop, and a USB to ALDL cable. There are many that will work out there, and anythign seeing live data from the ECM will help. This applies to both L98/LT1 cars. You need to see what the computer is seeing. Probing under the hood only tells have the story. You may see the reading out there, but doesn't mean that is reachign the ECM.
To help further, please let us know what year/engine you are working with. My guess would be you have a bad MAF or bad wiring causing a out of spec reading to reach the ECM. Any codes with it plugged in?
Last edited by KyleF; Jan 25, 2019 at 09:37 AM.
Thread Starter
8th Gear
Joined: Jan 2019
Posts: 8
Likes: 0
From: Denver
Ok the buttons on this keyboard are too close together. Not fighting the FPR meant to say been fighting this for a while. Other new items on the car, new Fuel pump, new relay for MAF, all vacuum leaks sealed (those are always fun). What I am seeing here. Since the limp home mode is working really well when the MAF is disconnected it seems like the TPS is working well, The knock sensor appears to be working, The Idle air valve appears to be functioning well
, I have to wonder if the computer program is messed up and needs to be reflashed. Have no idea how to do that with an 85 model. Its pretty easy to do in my 2001 but with this old system looks more complicated.
, I have to wonder if the computer program is messed up and needs to be reflashed. Have no idea how to do that with an 85 model. Its pretty easy to do in my 2001 but with this old system looks more complicated.
Melting Slicks
Joined: Nov 2007
Posts: 2,830
Likes: 147
From: Gainesville FL
Ok the buttons on this keyboard are too close together. Not fighting the FPR meant to say been fighting this for a while. Other new items on the car, new Fuel pump, new relay for MAF, all vacuum leaks sealed (those are always fun). What I am seeing here. Since the limp home mode is working really well when the MAF is disconnected it seems like the TPS is working well, The knock sensor appears to be working, The Idle air valve appears to be functioning well
, I have to wonder if the computer program is messed up and needs to be reflashed. Have no idea how to do that with an 85 model. Its pretty easy to do in my 2001 but with this old system looks more complicated.
, I have to wonder if the computer program is messed up and needs to be reflashed. Have no idea how to do that with an 85 model. Its pretty easy to do in my 2001 but with this old system looks more complicated.
Drifting
Joined: Jun 2018
Posts: 1,678
Likes: 229
From: Michigan
Without a scan tool to see what the MAF reading is, all you can do is inspect the wiring and swap in another known good MAF to isolate.
The computers in these cars have PROMs and not Flash memory like the newer computers. I am not sure a program on a prom can become corrupt. I have never seen/heard of this before. Anything is possible, but I would say that is a low probability and you need to start checking the MAF circuit.
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Le Mans Master
Joined: Sep 2013
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From: near the thumb in the mitten
MAF measures amount of entering engine. When it is disconnected ecm defaults to speed density based on tps. There are relays for MAF. MAF uses heated film . If the film is dirty it can give faulty readings and not set codes. Air leaks in duct from MAF to throttle body and vacuum leaks will cause lean conditions , because of unmeasurrd air entering engine. Monitoring MAF, TPS, O2, and short term fuel trim ( int) parameters would be helpful.
Thread Starter
8th Gear
Joined: Jan 2019
Posts: 8
Likes: 0
From: Denver
The MAF relay is new, Had no effect on driveability when replaced. The MAF itself is a rebuilt old school one The new versions simply would not work at all. Tried to make several work to no avail. So went and had this one rebuilt When installed error code went away and car started right up. That was when this issue came up
Drifting
Joined: Jun 2018
Posts: 1,678
Likes: 229
From: Michigan
The MAF relay is new, Had no effect on driveability when replaced. The MAF itself is a rebuilt old school one The new versions simply would not work at all. Tried to make several work to no avail. So went and had this one rebuilt When installed error code went away and car started right up. That was when this issue came up
Melting Slicks
Joined: Feb 2015
Posts: 2,069
Likes: 262
From: Park Ridge New Jersey
Drifting
Joined: Jun 2018
Posts: 1,678
Likes: 229
From: Michigan
This was why I said a "known" good one. Preferably off a friend's healthy running car. A scan tool would be preferred. See the readings between the different MAFs you have. If they are both the same readings at the ECM but out of spec, my guess would be in the wiring.
Last edited by KyleF; Jan 25, 2019 at 07:52 PM.