QuestionFOLLOW-UP (original question and answer at the bottom of this entry)
I changed the O2 sensor and nothing changed. But I noticed that there was some previous damage to the left fender and that a major electronic component located there might also be damaged. A $35 visit to the junk yard and 1/2-hour later, all trouble codes and "check engine" message gone (only codes were 12 cuz I disco'd the battery and 55 for end of messages).
BUT ...
"Maint Req" message is now on full-time. I don't know if this is just on a timer or ? or if it actually detects a problem somewhere. Also, van still cuts out when going uphill under heavy pedal effort. "Maint Req' light will go out during cut-out period but will return once the van recovers. Will recover when pedal effort relaxed. Stalled while idling at stoplight once, but started easily right away. Idles much smoother though with the replaced electronic board (I don't know if this is the ECM because there is another large electronic component on the top of the passenger end of the firewall).
I am suspecting maybe fuel pump b/c I did run it out of gas a while back, but the current pump is not making the "scratchy" whine they sometimes do just before they bite the dust.
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Followup To
Question -
Engine: 3.3l V6 with FI
Symptoms: Stalls at highway speed only when engine under load with heavy pedal effort, such as when going uphill. Does not stall at any other time, whether driving or at idle and will immediately recover when pedal is released or effort reduced enough, sometimes with a load tailpipe backfire. Idle slightly rough. "Check Engine" light on at all times.
Codes: Engine codes have been doublechecked using on-off-on-off-on procedures and recording the "Check Engine" flash rhythm.
12 computer memory loss/recent power loss
(Battery was disconnected during investigation)
17 runs too cool/doesn't heat up fast enough
(I live in a hot desert and sometimes remove the thermostat)
21 O2 sensor not responding
(time to spend $60)
43 Cylinder misfire or ignition control problem
(please brainstorm on this one?)
55 end of codes
(bdeep bdeep that's all folks thanks for watching)
I can understand all but #43 and wonder if it may be reporting misfire simply due to bad O2 sensor causing misfire? I'll replace O2 sensor and report back since #21 means it would like a new one.
This is mainly submitted to help others who may experience a similar problem but your feedback/input is warmly welcomed in the likelihood I am completely missing something! :-)
Thanks,
JimR
Answer -
Hi Jim,
Thanks for the very graphic history!
The code definition in '90 for the #43 actually is not misfire (though it is for the mid-90's and later) which you appear to have under load conditions but instead it specifically states that the primary winding of one (or more?) of the three windings of the spark coil pack is operating in such a manner that the maximum instantaneous current is below what would be expected to be reached. This implies that one of the coils may have excessive resistance or maybe the driver wire from the coil to the control module is not making good contact. You can check this out as far as the coil goes by measuring the resistance of the three windings to see if any of them are different from the other two. The nominal range is 0.45 to 0.65 ohms. The winding have a common 12V input. If you pull the plug to the spark coil pack you will see that it has 4 pins, and that 3 of then are adjacent to either the interal bulge or the external bulge of the shell. Those are the three coils' individual driver leads. The fourth pin is for the common 12V input to the other ends of the coils. So take a ohmmeter and measure the resistance between the common input pin and the three other pins and if you see that one is outside the spec value that would be a basis for buying a new coil pack. If you would like to check the driver wires from the harness side of the plug the three pins go respectively to pins 14, 15, 16, of the 60 way plug at the engine controller (hold the plug with the pins facing you, short tab up/long tab down, start counting with 1 at the left hand end of the top row) and verify that the resistances are all similarly low. If you want to check the secondary winding of the coil pack just measure the resistances between each pair of towers which should be in the range of 7,000 to 15,800 ohms each.
So that is how I would deal with the 43. And I agree with replacing the O2 sensor, then disconnecting the battery for a few minutes, then reconnect and drive the van to see if the 21 code is now gone, and with it the 43. And/Or verify the coil resistances, and if necessary replace the coil pack and see if 43 disappears after disconncecting the battery and driving if for a while.
I am curious to know what you learn.
Roland
AnswerHi Jim,
It sounds like you did replace the engine control module also known as the powertrain control module. It is nice that it solved many of the problems. On your problems with power going up hills I would wonder if the catalytic converter may be restricted as this is often experienced when that happens. You can check that with an air pressure gauge inserted in the oxygen sensor mounting hole. At 2500 rpm the back pressure should not exceed 1.75 to 2.00 psi ir that would suggest a restriction in the exhaust system. (But see another idea below).
The large electronic box on the firewall is for the transmission control. The maintenance required light sounds to me like a mileage reminder but I don't know for what purpose. I haven't seen that mentionned in any manuals that I have. Maybe it has to do with servicing the egr valve? By the way it would be good to check the egr valve for freedom of motion of its valve stem. Look for it on the right rear corner of the engine and you will notice a rod inside of an opening beteen the round top of valve and the main valve body. That rod had a slot in it so that you can observe its motion and also open and close the valve against its spring action by inserting a screwdrive blade in the slot. It should shut tightly but still open when operated by the vacuum system to which it is attached. Observe the valve stem for motion between idle and 2500 rpm. If it is sticky or slow to respond put some solvent on the stem where it enter the valve body to free it up. It may not be closing all the way at idle and at full throttle which it has to do or you will get a stalling at idle and a lack of power at full throttle. So that egr valve would be the first thing to check even before the catalytic converter.
Roland
