Engine stall at full stops intermittently, error codes unrelated.

alcyon

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#1
On friday night my 1g gte stalled at a busy intersection after about 40 mins of high way drive. It was embarassing and I tried to restart the engine several times, it cranked but wont fire up. I turned on the hazard lights and immediately thought of the AFM connector as this has happened before. I looked the the plug and it looked tight enough but I just unplugged it and replugged it, yet same , it would crank but wouldnt start. So I pushed the car on the opposite side of the road which had far less traffic. I checked the EFI fuse and AM1 and AM2 all were ok. So I unplugged the AFM again, looked at the pins, they were intact, so i pushed the plug in extra hard. I tried restarting and it fired up. I drove to my friends house, picked him up. Drove to another friends house, picked him up, went for drink, drove both of them back, then finally drove 40km back home with no incident even with stop and go traffic on the highway at one point. Boosted the turbo with no issues too.

Next day was driving to the wreckers to collect my parts, and as I was coming to a stop, in D, the engine stalled again. Tried restarting and it wouldnt, it would just crank but wont fire up. Pushed the car to the side, again checked AFM plug, pushed in real tight and tried to start, it fired up. Drove to the wreckers, after that drove home, through heavy stop and go traffic keeping my fingers crossed, and no incident . Got home safely. I suspect the Fc and E1 pins are having a bad connection causing the C.O.R to shut off.

That night, I took the AFM apart and had a look inside, sprayed CRC electronic cleaner and checked resistances. I put it all back together, and as extra precaution, I used a small flat head screwdriver to tighten the grip of the AFM female connectors so that it made better contact with the male pins on the AFM. I also tie wrapped the AFM wires at 2 places, one to the turbo lines and the other the power steering line, with some sponge to keep the heat away from the AFM cables. I did this to relieve the strain off the connector and wires as gravity has a tendency to pull down the wires and connectors which could cause bad contact in the AFM connector, since the AFM is bolted tight to the engine bay but the afm cables are attached to the engine which can twist side to side on the mounts hence pulling on the cables. I also found that the accordian hose after the AFM to the intercooler pipe was a little loose, I did not tighten the clamps enough, so i made sure they were tight this time.
Next day I took the car to a hilly residential area with very little traffic (bukit tunku - google it ) and put the car to a torture test. I boosted uphill over and over, braked hard uphill, downhill, trying to stall the engine. Did this for like 1 hr. Even reversed uphill and left it in R gear while letting the throttle off. I couldn't replicate the stall. I drove home again, without incident,but I was still weary if I really fixed the problem or not.
The next day i drove the car around, yet no stall issues. I remembered the diagnostic mode, so i made myself a little wire which i plugged to Te1 and E1, and looked at my check engine light. I was hoping to get codes that told me what caused the stall. Instead i got codes 24 and 34.
24 is AFM temp sensor
34 is turbo boost pressure abnormal.
Nothing related to ignition or coil.
I did try to start the car without the AFM plugged in ,could this have cause these codes to appear ?
Just to clear up :
The engine has no misfiring, it idles and runs smooth throughout its rpm range. boost comes on well and strongly with no hesitation, no indication that anything is wrong with the engine, yet I am getting these 2 codes. I pulled the EFI fuse and it cleared the codes, I plan to drive the car around with minimal or no boosting and see if any of the codes re appears. I have never noticed the CEL blinking or turning on before this yet when I checked for codes its there. I would have thought that the CEL would have lighted up to notify me to check for codes, but it didnt.
 
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3p141592654

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#2
34 is from fuel-cut due to over boost situation. I would think it is unrelated.

24 is more suspicious. You would need two drive cycles to set it. So it may point to your AFM wiring being intermittent.

Two things I would check: First does the tach move after it dies and you try to restart. If the tach is dead it points to bad CPS wiring (I don' t know if the 1G has a CPS or its part of the distributor, but its the same wiring in either case).

Second, if you suspect the AFM wiring, then with the car idling push and pull on the AFM connector and harness to see if you can make it stall. Could be a cracked wire internally to the harness that is intermittent.
 
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alcyon

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#3
Two things I would check: First does the tach move after it dies and you try to restart. If the tach is dead it points to bad CPS wiring (I don' t know if the 1G has a CPS or its part of the distributor, but its the same wiring in either case).

Second, if you suspect the AFM wiring, then with the car idling push and pull on the AFM connector and harness to see if you can make it stall. Could be a cracked wire internally to the harness that is intermittent.
Hard to tell if tach moves or not cause its digital and it blanks out when I crank, and thats normal digi dash behavior. However as soon as i let go start key to ON it will light back up and show the revs. So far the revs always show up and never has a dead spot.
I think 1G and 7MGE uses the same distributor system.
As for the AFM cables, I find it odd that the cables hardly have any slack in them, they are tugging very slightly on the connectors. I managed to find new connector with wires but I am weary of cutting the wires and soldering to new connectors, but looks like I might have to do it to relieve strain off the wires. I will buy a new connector this weekend and just solder them on to extend the wires a bit to give it some slack.
 
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