Hello all, I'm new to the forum and although I don't currently have an F body I did have an 86 T/A which was quite the fun ride. It had a high output 305 and it handled real well.

But that's in the past...now I have a 1940 Ford pickup that I have spent many years building and my mill of choice is a 4.3 TBI Chevy V6. The truck is assembled and running but it runs very poorly and won't idle correctly at all. I just took delivery on an OBD1 cable to use with my buddies Actron scanner and hope to get some useful clues as to why this thing runs like crap. So, I'm coming to this forum, hat in hand as a former F body, current GM guy and asking for some help.
The engine is a 4.3 Chevy with a model 220 throttle body, using yellow/ blue color coded injectors. I have modified the internal fuel pressure regulator to deliver 12 PSI from an external Holley TBI fuel pump. The computer is a '747 with a 16139566 PROM and a 16060837A Cal pack. The wiring harness is from Painless performance and the whole system is using Painless specified MAP sensor CTS, 02 sensor, EGR solenoid, knock sensor etc.

Right now the engine starts and runs but begins to surge between a near stall to about I'm guessing 2500 RPM as the engine warms, the surge gets worse and finally the IAC opens up and the engine just sits there and races at about 3000 RPM. There are codes 33, 34 and 44 present right now. I know none of this may be too helpful but if any one can chime in about things to look at, I would appreciate it a lot!

 

You have the wrong prom thats for a 5.7l

 

A Akdx will work I have a few if you can't find one. There are several others that will work as well.

http://www.ebay.com/itm/COMPUTER-CHIPS-ATKX-4-3-TBI-700R4-ECM-1227747-CHEVY-GMC-C-K-R1500-2500-TRUCK-/390490728972?pt=Motors_Car_Truck_Parts_Accessories&hash=item5aeb0faa0c&vxp=mtr

 

Thanks for the info. The PROM is the one that Painless specified. The one I took out was an AKMH, but it seemed to run better with the Painless specified PROM

 

The calpak should be a 16051636 you must be reading the number off the chip itself those will work on the 4.3, 5.7 and 7.4l

 

You listed a asdu that's from a 89 5.7l

The Akmh from the astro van 4.3 should be used if you have code follow the gm trouble tree or datalog using tunerpro $42.

You can diagnose with the Akmh and watch your map to see if that is the reason for the lean condition. You didn't state if this is a stock rebuild or has much of a cam to fluctuate manifold vacuum.

 

I bought the engine 2nd hand and it is supposed to have 54K on it, I checked compression when I bought it and it seems fine (150PSI per hole), nice and even.no bearing or tappet noises either, it came from an S-10. No cam that I know of but I'm leaning toward trying to measure the lift sometime If I can't find any other problems. Thanks

 

You can just use a vacuum gauge to see what manifold vacuum is. This could be a bad ecm, or bad ground for the ecm as well. But painless was not so painless when they told you to purchase a 350 prom.

 

I know low manifold vacuum and a lopey idle is an indication of a performance cam but this thing won't idle for crap I'm seeing anywhere from 4-5 inches up to 20 inches of vacuum while at "idle" because the speed is all over the place. Thank you for the information on the calpack, yes we were reading the number directly off the chip, the packaging from GM had the correct part number but my buddy was all jammed in about the difference in the numbers although he also pointed out as you did that the chip could have one part number and the assembly (chip & carrier) would have another.

 

Sorry I'm not much help, the 1227747 is not that expensive to try another one or prom. If thats not it sounds like possible bad 1 bar map or a a cam has been installed in this engine.

http://www.gearhead-efi.com/BCCFind/

http://www.robietherobot.com/storm/mapsensor.htm

http://www.hotrodders.com/forum/tbi-...es-155497.html

 

We got the Actron hooked up to the truck tonight and recorded data. I wish I knew exactly what I was looking at

I posted the data up on gearheadefi.com and the guy there said the data looks good but that doesn't explain why the truck runs so badly. My original estimates of speed were off... the data says the truck is idling at 1000 rpm. I will post the data below. This data was taken with the vss disconnected and the v8 prom installed per painless specs... I think I'm going to try going back to the 6 cylinder prom...don't know what it will do for me but what the heck. Tomorrow I'm going to try to set the idle speed again. I'm shooting for 650-700 rpm. One good thing I got from the data is that the engine temperature is at about 190 degrees, not the 230 that my cheapo Dolphin gauge is reading. But maybe the reading on the gauge is higher because my sender is in the side of the head, near the exhaust ports? Here's the data:


1989 Astro/Safari
Z=4.3L TBI

Vehicle Data List


CODES PRESENT NO
3RD GEAR SW ON
AC REQUEST OFF
AIR DIVRT SOL DIV
AIR SW SOL CONV
BATTERY(V) 13.8
BLM 114
CLEAR FLOOD OFF
COOLANT(øF) 192
ENGINE RPM 1000
EXHAUST 02 LEAN
HIGH BATTERY NO
IAC POSITION 74
INTEGRATOR 127
LOOP STATUS CLSD
MAP(V) 2.04
O2S(mV) 719
O2S CROSSCNTS 246
P/N SWITCH P/N
PROM ID 9461
TCC LOCKUP NO
TCC SOLENOID OFF
TPS SENSOR(V) 0.65
VEHSPEED(MPH) 0
Frame: 0 Time: 0.0

CODES PRESENT NO
3RD GEAR SW ON
AC REQUEST OFF
AIR DIVRT SOL DIV
AIR SW SOL CONV
BATTERY(V) 13.7
BLM 114
CLEAR FLOOD OFF
COOLANT(øF) 192
ENGINE RPM 1000
EXHAUST 02 LEAN
HIGH BATTERY NO
IAC POSITION 74
INTEGRATOR 126
LOOP STATUS CLSD
MAP(V) 2.06
O2S(mV) 98
O2S CROSSCNTS 246
P/N SWITCH P/N
PROM ID 9461
TCC LOCKUP NO
TCC SOLENOID OFF
TPS SENSOR(V) 0.65
VEHSPEED(MPH) 0
Frame: 1 Time: 1.1

CODES PRESENT NO
3RD GEAR SW ON
AC REQUEST OFF
AIR DIVRT SOL DIV
AIR SW SOL CONV
BATTERY(V) 13.7
BLM 114
CLEAR FLOOD OFF
COOLANT(øF) 192
ENGINE RPM 975
EXHAUST 02 RICH
HIGH BATTERY NO
IAC POSITION 74
INTEGRATOR 127
LOOP STATUS CLSD
MAP(V) 2.08
O2S(mV) 861
O2S CROSSCNTS 248
P/N SWITCH P/N
PROM ID 9461
TCC LOCKUP NO
TCC SOLENOID OFF
TPS SENSOR(V) 0.65
VEHSPEED(MPH) 0
Frame: 2 Time: 2.3

CODES PRESENT NO
3RD GEAR SW ON
AC REQUEST OFF
AIR DIVRT SOL DIV
AIR SW SOL CONV
BATTERY(V) 13.8
BLM 114
CLEAR FLOOD OFF
COOLANT(øF) 192
ENGINE RPM 1000
EXHAUST 02 RICH
HIGH BATTERY NO
IAC POSITION 74
INTEGRATOR 127
LOOP STATUS CLSD
MAP(V) 2.04
O2S(mV) 768
O2S CROSSCNTS 251
P/N SWITCH P/N
PROM ID 9461
TCC LOCKUP NO
TCC SOLENOID OFF
TPS SENSOR(V) 0.65
VEHSPEED(MPH) 0
Frame: 3 Time: 3.4

CODES PRESENT NO
3RD GEAR SW ON
AC REQUEST OFF
AIR DIVRT SOL DIV
AIR SW SOL CONV
BATTERY(V) 13.7
BLM 114
CLEAR FLOOD OFF
COOLANT(øF) 192
ENGINE RPM 975
EXHAUST 02 RICH
HIGH BATTERY NO
IAC POSITION 74
INTEGRATOR 127
LOOP STATUS CLSD
MAP(V) 2.08
O2S(mV) 795
O2S CROSSCNTS 0
P/N SWITCH P/N
PROM ID 9461
TCC LOCKUP NO
TCC SOLENOID OFF
TPS SENSOR(V) 0.65
VEHSPEED(MPH) 0
Frame: 4 Time: 4.5

 

I'm not sure why painless would tell you to use a v8 calibration on a v6. The idle map volts look good around 40kpa. With the engine temperature at idle air control count is high. Frame 4 no o2 cross counts . You might want to use tuner pro for a log since the refresh is slow.

 

You mentioned that the IAC count is high, I'm guessing that this would contribute to my fast idle situation. I'm going to try to go through the base idle setting again tomorrow. I'm really hoping to be able to get this thing to run. Does anyone think there might be a vacuum leak I just cant find?.. I have looked at every vacuum related thing on the engine. There's no vacuum advance, the MAP vacuum is connected to the right place, the PCV vacuum is connected correctly as well. The EGR vacuum has been connected to my vacuum gauge (15 inches @ 1000 rpm) and the port that went to the brake booster in a past life is plugged as is the port that went to the charcoal can. I have sprayed carb cleaner around trying to get it to to change to no avail but it's sure acting like a vacuum leak!

 

You were told 6 days ago you had an 8 cylinder chip in a 6 cylinder engine and your still asking for help on 2 different forums?

Yes I told you the data looked good, I also told you had a 8 cylinder chip in a 6 cylinder! Why are you still looking for something else to fix?

 

 

Ok guys! I'm listening! The only thing worse than dealing with a thick-headed Italian is dealing with a rookie thick-headed Italian. Today I'm going to put the 6 cylinder chip back in and set the base idle again. I appreciate your patience with me, I know I have not been the most logical troubleshooter out there and I am thankful for forums like Gearhead efi and Thirdgen. I promise to behave myself and do what I'm told

Thanks!

 

Just a warning DIY efi gear heads travel in packs lol

 

In this case, that's a good thing. If there was just one of you, I would drive you crazy

 

Please don't tell us your trying to adjust idle with the Minimum Air Adjustment Screw?

 

I have a procedure in the Painless manual:

Turn on ignition but do not start engine
Jumper A&B of the ALDL as if you were checking codes
Wait 30 seconds and then remove the plug from the IAC motor
Remove the jumper from the ALDL
Start the engine and adjust the idle speed with adjusting screw at the throttle lever
Shut off engine and disconnect battery for one minute
Plug the IAC connector back in and then reconnect the battery
Start the engine and check for proper idle speed

Is this not correct?

 

Do it warmed up. Then check IAC counts after a drive when you come to a stop. Stock motor under 30 IAC counts is fine.

Idle RPM in this ECM has much more control in Drive then Park or Neutral. Does the Painless manual still say to ground the Park/Neutral wire if no switch is in place? It should be open, I told them that years ago...

You've got bigger fish to fry right now then idle.

 

Thanks for the reply. According to the Painless manual, the way it is wired puts the org/blk park/neutral wire to ground only when the truck is in park.

 

 

Today I ran the engine with the 6 cyl PROM. Ran bad till it warmed up then it ran better. I had made a boo boo when I stated that the EGR vacuum was terminated. The egr vacuum was connected to the EGR solenoid and the engine was seeing some EGR action at idle. We plugged the EGR vacuum line and the engine ran smoothly!!! We went through the base idle setting again and set the idle for about 750 RPM. When we restarted the engine after the idle setting, the idle was again up to about 1000. Strange.

Another strange thing was that the scanner said that the vehicle speed was 0 and the TCC was off, until you tried to move the truck, then as soon as it was in gear, the TCC was on and the MPH was like 240 MPH when we were barely moving. At this point I disconnected the VSS and the scanner reported that the TCC was off and the speed was obviously "0". The VSS is the stock one that came with the TH700R4 and apparently not the 2PPR VSS that Painless calls for in the manual (my goof) I don't know how many PPR the stock VSS puts out but my GM wiring diagrams show that the VSS is not connected directly to the ECM in the stock truck, there seems to be a digital ratio adapter and some sort of buffer for the signal before it reaches the ECM. I went to the Painless web site and they do sell a VSS with the correct PPR but from the photographs in their catalog, it looks like a unit designed to fit in place of a mechanical speedo cable. I will check with them tomorrow. When you look in the Painless catalog, they say that the VSS they sell is for the TBI application but they make no mention of the transmission it fits

I would consider today a day of slight progress in that we got the engine to straighten out and run with a good steady vacuum (22 inches) but I'm still not sure how to get it to idle at the right speed. Also, the transmission is still exhibiting problems. We set the TV cable again by bottoming it and then using the gas pedal to push the throttle to WOT and the cable self adjusted but you have to stick your foot in it bad to get it to shift to 2nd and it never went to third. I need to recheck the brake switch wiring to be sure that the power for the TCC is cut off when the brake is depressed.

 

Your best bet might be buying a Dakota digital sgi-5 the tbi with the 747 uses a 40 pp revolution and the drac converts the signal to a 2k optical signal.

 

Ordered the SGI 5 tonight, it looks like it will fix things. I was amazed that Painless offered a converter for older transmissions that had a cable drive but they had nothing available for a 700R4 with a VSS in it already. They told me to go back to the donor vehicle and get the speed buffer. Funny there's no mention of needing to convert the signal from the VSS in their manual. I spent many years as an electronics technician and right about now, it's looking like I would have been way ahead of the game if I had just stripped the harness out of the donor vehicle and figured it all out on my own

 

a vss buffer from a thirdgen tbi car would work but would not give you the speedometer correction like the sgi-5.

 

I had been doing some more snooping and discovered that the TBI unit I'm using has more play in the throttle shaft than it should. I'm thinking that I may have swapped the throttle lever I wanted to use onto the wrong throttle body when I set this thing up years ago. Anyway, last night I went through the throttle bodies that I had and found one from a newer truck (mid 90's) I think but it still looked like a model 220 TBI unit. I soaked it in cleaner all night and assembled it this morning using the fuel metering unit from the TBI in the truck because it has the right injectors. I assembled the "new" throttle body today and when I installed it, that engine would idle so slow you could hear the individual injector clicks! I set the minimum air and idle speed according to the GM procedure and since this is an OLD (1989) pre-Vortec, pre-balance shaft engine, I had to find a sweet spot where the idle was as smooth as it was gonna get without just plain running it too fast. I know these weren't the smoothest idling engines in the world but it doesn't make much difference when the truck is parked at a cruise night . I still need to put the scanner back on there and look at my IAC count but I'm confident that it is in the correct range now.

I just received a Dakota Digital SGI-5 Universal signal interface unit to get the right pulse rate from the VSS in the transmission to the ECM. My Painless Performance manual did not say that the ECM wouldn't work with the stock VSS built into the transmission unless you used the factory speed buffer, which went to the big swap meet in the sky with the donor truck. Once I get that set up, I should be able to reconnect the VSS and not have the scanner tell me I'm doing 244 MPH crawling up my driveway and the instant TCC lockup should go away too. Then I need to get it to the guy who did the transmission to see why it wont shift correctly despite having set the TV cable according to the GM procedure.
Again, thanks to all!

 

when adjusting the TB cable dont mash the gas pedal with your foot, bottom it out, then bring the Throttle linkage to WOT by HAND, thats what i did and it worked perfect, when i did it the same way you did it never shifted right

 

I just played with the TV cable. When I adjust it like you said (which is the way I was taught to do) the cable doesn't even move on click and the truck never gets out of 1st gear. When I adjust it by pushing the pedal to the floor, the cable moves about 3/8 of an inch. I just bottomed the cable, disconnected it from the throttle lever, pushed the lever to WOT by hand and then pulled the cable out until the cable connector was in line with the stud on the throttle lever. This resulted in the cable adjuster coming out about 3/4 of an inch. I have been told that the farther out the cable is from the bracket, the softer and sooner the shift so at least this method of setting the cable yields a result in the right direction. I will try driving it in the daylight tomorrow.

 

Hi all! Happy Spring!

I'm still sorting out my 4.3 TBI engine in my 40 Ford pickup. Right now, I'm looking for a source for a custom calibration for the PROM that will set the idle speed to about 725 RPM. Currently the idle speed is about 600-625 ( I have a small diameter tach that's not too easy to resolve small increments).The engine is a pre-balance shaft unit and since it is transplanted from a S-10 to a Ranger frame with a 40 Ford body on it, it is a little short of optimized as far as the harshness of engine vibration telegraphing throughout the truck when it's in drive. With the engine idle set to about 725 RPM. It seems smooth enough and the truck doesn't creep too badly in drive. I arrived at the 725 by adjusting the minimum air adjustment screw to arrive at a suitable idle speed. From what I can tell, this is not an acceptable method of setting the speed since it is overriding what the ECM is telling the engine to do and the reason that the engine stays at the set speed is because since I'm adjusting the minimum air screw, there's a corresponding change in the voltage from the TPS, so the computer just thinks I have my foot on the gas a little. The down side of this is that the idle speed is not under control of the ECM and it approaches 900 RPM in park and I assume that it will load down below 725 RPM with the added load of the AC compressor when I finish the installation of the AC. So I'm looking for a way to keep the idle speed under the control of the ECM via the IAC and I guess that means a custom PROM.

Also, the transmission is still having a problem although it now shifts through the first 3 gears OK, 4th is only obtainable by letting off the gas at cruising speed but it goes immediately back into third if you put your foot back on the pedal and try to cruise in 4th. The guy who built the transmission seems to be scratching his head over this. He fiddled with the TV cable when I brought it back to him and now it shifts worse than ever. I'm going to try another tranny shop. But I do have a question about the transmission too: I have a 700R4 and a 3.45:1 rear axle ratio, the truck lurches very easily when you try to accelerate from a stop, it's very frustrating. The guy at the transmission shop said that he thought that it feels cool that way and it was a result of my rear axle ratio and the low 1st in the 700R4. I'm not buying it and I think there's a problem with the torque converter or possibly the wrong torque converter was installed. The original axle ratio from the donor truck that this transmission came from was 3.23:1 IIRC and that's not that different from a 3.45:1. Can anyone shed some light on any of the stuff I'm asking about?

It's getting to be the time of year to get this thing out of mothballs and ready for another season. Even though some of the mechanical issues dogged me last season, the truck actually garnered 2 awards at shows last year, I was totally unprepared for that, since I never intended to be competing at all. I'm not sure exactly what the judging criteria was at those 2 shows, since I have never filled out a judging sheet!