E150 1992 302 EFI

Hi again.... Engine hesitates on low RPM's. New EGR valve and EGR solnoid. (Not new EGR sensor) No code. Runs much better with vacuumline to EGR valve off. But then the CEL light
comes on of course and uses much fuel. New wires and cap and rotor and plugs and AIC valve and canister purge valve. Timing checks OK several times. I can't really figure out what is doing this. Have read about a PFE or DPFE transducer which maybe can have anything to do with this. Where is that located in the engine? Maybe a bad PCM or ECU or what it is called? Can anyone please help?? Regards, Tor....
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Why did you suspect EGR in the first place?
I Think you are looking at the wrong thing.
Remove the harness connector from the MAF.. see if it runs better without.
If it does, clean the MAF.. google for directions.
If it doesnt, it MIGHT be the Throttle Position sensor.
I assume, because you didnt mention otherwise,that the engine starts and idles fine at all temperatures.
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Where is this MAF sensor? I thought this one had an MAP sensor, and that one I have changed. (Not possible to open) Trottle position sensor also changed. Nothing happened to the better. Regards, Tor.
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On Mon, 04 Sep 2006 04:18:44 GMT, Backyard Mechanic

Backyard, IIRC, the '92 was still speed density - no MAF. I had the problem he describes a couple of times and found the EVP sensor was the culprit - not the EGR valve or solenoid. The sensors tend to get to the edge of specs and the ECM still sees good numbers to work with but, the EGR is more open than the sensor indicates resulting in a leaner mix and a resulting stumble. I have not seen one set a code like this. The problem is usually accompanied by a very slight surge around 15-1700 rpm at light load. The EGR valve itself is one of the more reliable components of those systems. I have also seen this when the port from the EGR to the throttle body is plugged.
Lugnut
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Hi lugnut..... Thank you for giving some answers. Have you read all my explanations here? When you talk about the EVP sensor could be the culprit. Do you then mean the sensor on top of the EGR valve? Do you mean that this sensor could give wrong signals and the the EGR opens because the sensor says that now you are closed? Am I understanding you right? Because then this may be the culprit. Sorry if I write bad english, but I do the best I can. Regards, Tor.
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On Mon, 4 Sep 2006 20:56:56 +0200,

YEs. The sensor voltage is supposed to increase as the valve opens. If the voltage increases within a readable range, the ECM assume everything is OK and opens the valve to obtain the correct signal for the engine operating conditions. If the signal is incorrect, the ECM has no way of knowing. This results in the valve being opendd too far. This is the EVP (exhaust valve position) sensor on top of the EGR. That is much more likely to fail tha the EGR valve.
Lugnut

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Hi again Lugnut.... Then I understand you correct. I will send request for buying a new one to the dealer right away. I will come back to you with an answer in a couple of days about how everything works. I like everything to be in good shape so that I have changed alot of things is OK for me, because then I know that they are in good shape. But nothing of the things I changed really corrected the problem. Hope the sensor will fix it then. When you explaned in the way you did for me now it is hearing very correct. I'll be back. Regards, Tor.
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Hi again Lugnut. I have now changed the sensor on top of the egr valve. But I have still the same problem. Run much better on low rpm's end at idle with vacuum to the egr valve off. Have checked ohms from trottle position sensor and AIT , and they seems OK. The EGR solnoid has vacuum to it all time coming from the other 2 solnoids. (Thermactor Air diverter solnoid and Thermactor air bypass solnoid.) I am not shure how these solnoids work together etc. But nothing seem to cut of the vacuum in to the EGR solnoid at any times. Is that correct? Do you have any further ide's? Regards, Tor.

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snipped-for-privacy@handicapsiden.no wrote:

bucks. Did that EGR come with a whole bunch of little washers that you threw in the trash? I dont think that old of an engine had the dpfe yet, not sure though. You could look at a parts place to be sure. were there washers?
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No washers in the trash, and everything is put back together exactly as it was done with the old one. Red plastic washer under the sensor, and there are no leak there. The fuelfilter is changed. It seems for me that there are something wrong with signal for trigging the vacum to open the EGR valve. On idling and low RPM's there are to much vacum in the line to the EGR and the valve is opening and as far as I know it shouldn't open that early. Should only open at high RPM's. I am wondering a little about that I maybe can have an bad connection to the MAP sensor. The MAP it self is changed and new. Or maybe something bad in signals from PCM. If there is nothing else that can trigg the vacum to the EGR at wrong circomstances . The IAT is new and seems for me to work OK. Also the TPS sensor is changed with no changing. There also seems to be no vacum leaks. And no clogged EGR passages. IAC is new and seems to work fine. The ICM is new and seems OK. The things I have left to think of is something with connections to MAP, something with distributer, or PCM as far as I know. Anyone have other thing they think about? Regards, Tor.
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snipped-for-privacy@handicapsiden.no wrote:

The egr will open at lower rpms under load but never at idle .
the egr sensor is on top of the valve right? (cant remember 92 is kinda old)If so, try a little experiment. Remove the gasket between the sensor and the valve. this will make the sensor think the valve is opening faster/more than it really is...see how it runs like that.
you say it runs good with the egr unplugged...this could mean the egr OR you are just covering up a lean condition or even an ignition problem.
It wouldnt hurt to run some injector cleaner though it too just in case...
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