94 Trans Sport 3.8 no power, stalls...

[scottd60]

I have the 3.8 by the way if you didn't figure that out

If you remember back in my earlier post I cleaned the IAC and had to adjust it since it was pretty far out of adjustment...it did improve but was only short lived. The EGR was replaced a few years ago, the IAC has never been replaced...maybe it's time. Not too expensive and couldn't hurt even if it's not the main problem. Somthing hangs up in the idle control when it is 1st started after sitting a long while but usually frees up after 5-10 minutes but still is not 100% and will still occasionally stall.

Thanks,
Scott

Originally Posted by LMP

QUad driver faults just says the voltage condition at driver output is out of normal range. Drivers (grouped in pack of four in a single module, hence QUAD) are transistor acting as switches that are used to ground a circuit fed by 12V . Voltage condition at driver is high (12V) when circuit is unenergized hence not grounded, and falls to near ground voltage, like 0.5 V, when driver is energized.

so..either the circuit (generally a solenoid coil) tied to the unergized driver is open and no 12V is seen at driver input

or driver is "thought" to be energized hemce voltage should be 0.5V, and driver transistor is shot (rare..in fact almost unheard of) and does not ground the circuit, hence voltage stays high.

QDM error does not tell the driver is faulty, just that the voltage condition read at QDM is not what it should.THe first condition is generally the one that prevails in most faults .

BOth definitions for the codes you have are mindboggling though. THe only "heater" I see in this engine is the O2 sensor heater.....but other codes would reveal that in a more explicit way...and this would not act on a cold engine idle...

Drivers are used to control the step motor that sets Idle (Idle AIr Valve) ....I'd be tempted to look in that direction. www.avigex.ca/xport/fuelcontrol_iac.jpg Faulty air idle valve operation could cause high idles as well as stalls ...
ALso notice that vacuum leaks cause high idle.

[Jrs3800]

Code P0123 Throttle Position Sensor Circuit( Signal High Voltage )

Circuit Description
The throttle position sensor provides a voltage signal that changes relative to throttle blade angle.. Signal voltage will vary from .2 to .74 at idle and 5v at WOT.. Throttle Position Signal is one of the most important inputs used by the PCM for fuel control and for most of the PCM control outputs

Trouble Code P0123 will set when
Throttle Position Voltage is greater than 4.8v at any time or
Engine is running and air flow is less than 15 gm/sec
TP sensor signal voltage is greater than 1.1 volts
DTC P0101 Not present
All conditions met for 5 seconds

PCM will default with code P0123 set and not allow cruise control, 4th gear or TCC operating



Code P0401 Exhaust Gas Recirculation Flow Test Failure
The PCM tests the exhaust gas recirculation valve by momentarily commanding the vale ON while monitoring engine RPM.. If the expected drop is not see for a calibrated number of tests, the PCM will set the Check Engine light

The PCM will run the EGR tests when the following conditions are met
Codes P0122,P0123, or P0501 not set
Engine coolant temp is over 185 F
Throttle angle is over 1%
Brake has been applied
Vehicle speed above 25 Mph
Engine speed between 900 and 1100 Rpms


Code P0406, For this Van there is no code 406... The is a Manufacture specific code P1406

Exhaust Gas Recirculation Valve Pintle Position Error

The PCM constantly monitors the EGR valve pintle position sensor to ensure that the valve is responding properly to commands from the PCM

P1406 will set when
EGR pintle position indicates a voltage out of the normal range of the pintle position sensor, or a signal that is 10% greater or less than the PCM's commanded position

Either condition for up to 20 seconds



Code P0640 is actually P1640

This is Quad Driver Circuit #1, There are only 2 things on this circuit, this would be the TCC Solenoid and the EVAP Purge Solenoid..



Code P0670 is actually P1670

This is Quad Drive Circuit #4

The AC Relay
Fan #1( Puller Fan, Radiator side )
Fan #2( Pusher Fan, Condenser side )

Are on the QDM #4 Circuit


I hope this gives you a little bit of a direction to go in..

[scottd60]

Ok I changed the IAC...probably a waste of money since it didn't really change anything. Idle is high then low...still stalls out a lot. I checked the TPS and it didn't look good...on the scanner while viewing conditions it didn't seem to respond. Checked with VOM as well pretty much no responce and looking across B & C the resistance was way high not 1.5K-4.5K but 80K or better. I changed the TPS and all looks good the power is back, idle is good and so far no stalls. I reset/erased all the codes with the scanner and after about a minute or so the SEL came back on and the same 2 codes came back.

P0640 Quad Driver Module QDM 1 Fault
P0670 Quad Driver Module QDM 4 Fault

The van is running great...these codes must have to do with something else. I didn't mention this before but the AC is not working...I'm pretty sure the clutch assembly/bearings are shot and it is locked up. It spins and sounds nasty but the clutch is not cycling.

Any ideas...

Thanks,
Scott

[LMP]

Car runs great....great!
THe remaining codes have no references in the books for that car.

JRS3800 suggested they were 1640 and 1670 instead:
Code P0640 is actually P1640
This is Quad Driver Circuit #1, There are only 2 things on this circuit, this would be the TCC Solenoid and the EVAP Purge Solenoid..
Code P0670 is actually P1670
This is Quad Drive Circuit #4
The AC Relay
Fan #1( Puller Fan, Radiator side )
Fan #2( Pusher Fan, Condenser side )
Are on the QDM #4 Circuit
and with the info you have just added about the A/C , I think this is plausible.
I'd check refrigerant pressure when spring comes. (not relevant to check that in the cold as pressure would be much below specs anyway).
IN the mean time, I'd bypass the a/c compressor with a shorter belt:
With A/C the serpentine belt is 102.5", PN 1025K6. With out A/C the belt is 72.5", 30" shorter, PN 725K6.

[scottd60]

thanks for the info on the belt...I'll swap that out and see what happens.

My main concern was to get it running and get my emissions test done and hopefully pass. No such luck, while it seems to be running very good it did fail the emissions test with high NOx...read 5.1517 GPM (state standards 2.6000 GPM) all other test passed. I have until July 2nd to get it tested again or come up with $300 worth of receipts to get a waiver.

The test station told me to look at the following for failed NOx:
A/F mixture may be too lean
Oxygen sensor bad
Faulty EGR
Malfunction of engine spark advance system
Air intake temp too high
cooling system not functioning properly
carbon deposits on intake valves
catalytic converter partially clogged or not functioning properly

Any ideas?

Thanks,
Scott

[LMP]

ABout the A/C, also disconnect the pressure valve near radiator passenger side. THis is just to avoid having another code if pressure is oK and it tries starting the compressor while is has no belt.

FOr the rest:
A/F mixture may be too lean...that would be a consequence of the next.
Oxygen sensor bad..???....or out of scale....possible
Faulty EGR..would definitely have a code for that; dismissed
Malfunction of engine spark advance system....relevant...but improbable, I think..other codes would pop , like knock sensor..
Air intake temp too high...irrelevant in the conditions you operate
cooling system not functioning properly...doubtful..you would have other symptoms
carbon deposits on intake valves....long shot...wow..not going to lift the heads for that...dismissed
catalytic converter partially clogged or not functioning properly...well..this is a possiblity
Not mentioned, failed injector(s)....would push computer control range to limits and would propably pop a code...but a possibility anyway, or compensation might lean or richen ALL the injectors to acheive average O2 contents, but some would be lean, some rich...and Nox does not average....THis is easy reach....personnally, I would check that just to be sure not to have dismissed something easy..
There is an aluminum smelter here pouring 1.3 million tons of CO2 + xxx in the atmosphere every year...and they peek in my exhaust....

[Jrs3800]

Scott, just a small question for you..

For the Scan Tool that was used for the van, Will this Tool read the Live Data?

as the Miles on these 3800's add up the O2's get really sluggish and will not trip a code until the O2 is almost DOA.... We have seen a lot of the 94-96 3800's run 60k and have the sensors slow down causing a rich condition of sorts.. Keep in mind you will want to see what the sensor is doing before calling it bad..

In some cases a scan tool can be a great thing to have when working on these 3800's or any car for that matter..

[scottd60]

Originally Posted by Jrs3800

Scott, just a small question for you..

For the Scan Tool that was used for the van, Will this Tool read the Live Data?

as the Miles on these 3800's add up the O2's get really sluggish and will not trip a code until the O2 is almost DOA.... We have seen a lot of the 94-96 3800's run 60k and have the sensors slow down causing a rich condition of sorts.. Keep in mind you will want to see what the sensor is doing before calling it bad..

In some cases a scan tool can be a great thing to have when working on these 3800's or any car for that matter..

Yes, my scanner reads live data...I was able to look at the TPS and verify it was bad and also that the new one was working properly (also looked at it with VOM as well). Here is a link to the owners manual...I have the Actron CP9145 Super AutoScanner http://www.actron.com/publish/2005/0...lish_16150.pdf All the live monitor points are listed in the last couple pages of the manual.

You are right...having a scanner is a great tool and well worth the money. The one I purchased was a great deal and is also good to use on all the cars in my family so that is a plus. I also have an on-board Scanner permanently mounted in my 1989 Pontiac Turbo Trans Am (20th Anniversary/Indy Pace Car). It is a Scanmaster...taps into the diagnostic port and displays pretty much everything. I use it to adjust IAC, TPS and minitor AIT, RPM, ect. and mainly degrees of knock, the main killer of head gaskets and engines on these turbo engines especialy when turning up the boost!!! By the way the engine is the (if you didn't know) Buick 231 (3.8L) Turbo V6...same engine used in the Grand National currently running about 18# boost and soon to be 25-28# but that's another story and big new turbo

Scott

[Jrs3800]

I have that Tool Too Scott... Its comes in really handy for the 95 and under GM cars... I also have the older CP9110.... But I would like to have the CP9190, I think it is.. It will do Generic and Enhanced OBDII which is good..

Cant tell you how many times the tool has come in handy.. Heck it has even shown me the cylinder that was misfiring on the 94-95 3800's...lol


And Ahhh yes, we love the GN 3.8's as thats where GM learned a lot about the 3.8 and developed the 3800.. I think this is one of the reasons 3800's were such a good engine... Still are

[scottd60]

back again...the TPS (aftermarket) I replaced back in Feb has failed...car never passed emissions...have a extension till Oct now. Replaced the AC belt like suggested and unplugged the pressur valve (I think). No more squealing AC compressor clutch bearings...no AC either. Still throwing the Quad Module code ? Getting a replacement TPS from autoparts store...they are going to do it under a warranty. Also what should the O2 be reading on the live data mode in my scanner...I would think a good O2 would be around .750-.850...mine is reading ~.450 ? If that is bad I'm hoping this is the cause of emissions failure?

Thanks,
Scott

[Jrs3800]

Originally Posted by scottd60

back again...the TPS (aftermarket) I replaced back in Feb has failed...car never passed emissions...have a extension till Oct now. Replaced the AC belt like suggested and unplugged the pressur valve (I think). No more squealing AC compressor clutch bearings...no AC either. Still throwing the Quad Module code ? Getting a replacement TPS from autoparts store...they are going to do it under a warranty. Also what should the O2 be reading on the live data mode in my scanner...I would think a good O2 would be around .750-.850...mine is reading ~.450 ? If that is bad I'm hoping this is the cause of emissions failure?

Thanks,
Scott

The Voltage should swing.... You should be in the .100 - .900 area with the swing and see see the O2 cross counts... Something like this... Your van uses the exact same O2 as my Car..

[Jrs3800]

I almost forgot.... If you do buy an O2 sensor... Stay far far away from Bosch...

Either get the Denso, or AC Delco AFS-75

[96tsport]

Originally Posted by Jrs3800

I almost forgot.... If you do buy an O2 sensor... Stay far far away from Bosch...

Either get the Denso, or AC Delco AFS-75

Too late for me ..just changed the front one with ..Bosch..

[scottd60]

Originally Posted by Jrs3800

I almost forgot.... If you do buy an O2 sensor... Stay far far away from Bosch...

Either get the Denso, or AC Delco AFS-75

Originally Posted by 96tsport

Too late for me ..just changed the front one with ..Bosch..

same for me...only have a upstream O2 and it has been replaced with a Bosch as well O2 numbers look good on the scanner.

Installed new TPS and O2...seems to be running pretty good again...still getting the Quad Driver Module codes P0640 & P0670...can't figure out what they are?

[Scrapper]

i bet it's the iac. have you tested fuel pump or maf?