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Discussion Starter #1
got a insufficient egr flow code, the ecm is providing constant ground to the vsv vacuum valve, preventing egr operation, all vac lines are good, running at 2500 rpm, can block line at vsv, and egr operates, vsv does turn to no vacuum with key off, one weird thing, i scan the map sensor, the barometric readings are at say 2000 rpm, 8 inches of vacuum, in revving up to 3500 rpm, my vac gauge is reading 19 inches vacuum, scanner still shows 9 inches, i tried a autozone map sensor, the readings came up the same, low numbers, since the ecm is maintaining a ground, keeping the vsv port open (no vacuum), is the ecm at fault? or could it be reading something else, like wrong map?
 

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got a insufficient egr flow code, the ecm is providing constant ground to the vsv vacuum valve, preventing egr operation, all vac lines are good, running at 2500 rpm, can block line at vsv, and egr operates, vsv does turn to no vacuum with key off, one weird thing, i scan the map sensor, the barometric readings are at say 2000 rpm, 8 inches of vacuum, in revving up to 3500 rpm, my vac gauge is reading 19 inches vacuum, scanner still shows 9 inches, i tried a autozone map sensor, the readings came up the same, low numbers, since the ecm is maintaining a ground, keeping the vsv port open (no vacuum), is the ecm at fault? or could it be reading something else, like wrong map?
I don't know much about cars and don't have a clue if I can help anyone on this thread but I had a P401 code come up and the mechanic had a very hard time diagnosing it.He finally figured out(now I believe this is what he said but not 100%)that he there was some kind of glitch in the readings he got and it ended up being a solenoid,he replaced it and it runs great now.
I don't understand much and if you guys get anything out of this post I would be surprised lol
 
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got a insufficient egr flow code, the ecm is providing constant ground to the vsv vacuum valve, preventing egr operation, all vac lines are good, running at 2500 rpm, can block line at vsv, and egr operates, vsv does turn to no vacuum with key off, one weird thing, i scan the map sensor, the barometric readings are at say 2000 rpm, 8 inches of vacuum, in revving up to 3500 rpm, my vac gauge is reading 19 inches vacuum, scanner still shows 9 inches, i tried a autozone map sensor, the readings came up the same, low numbers, since the ecm is maintaining a ground, keeping the vsv port open (no vacuum), is the ecm at fault? or could it be reading something else, like wrong map?
:welcome:Remove your EGR and clean it. Clogging of the vacuum port going to the bottom of the modulator and the pipe going into the intake manifold are much more common issues. Also clean out the passageway in the intake maifold itself. If that doesn't work, let us know.
 

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:welcome:Remove your EGR and clean it. Clogging of the vacuum port going to the bottom of the modulator and the pipe going into the intake manifold are much more common issues. Also clean out the passageway in the intake maifold itself. If that doesn't work, let us know.
That sounds like the smart,cheap first move.I had forgotten that I tried that first,unfortunately in my situation it didn't help,but at least it was cleaner than it was and probably needed to be cleaned out anyways.
 

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Discussion Starter #5
p0401

yeah, i thought about the flow, i pulled the egr, pipe, cleaned and checked flow, reassembled and same results. the low map readings are questionable, at 2000-4000 rpm my vacuum gauge reads 17-20 inches, ecm showing 6-9 on scanner, would this be too low for egr operation?
 
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yeah, i thought about the flow, i pulled the egr, pipe, cleaned and checked flow, reassembled and same results. the low map readings are questionable, at 2000-4000 rpm my vacuum gauge reads 17-20 inches, ecm showing 6-9 on scanner, would this be too low for egr operation?
Put a vacuum pump/gauge on the port for the EGR diaphragm. Pull a vacuum and see if it holds. If the diaphragm is ruptured, that will explain your low readings and the valve will not open either.
 

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Discussion Starter #7
egr

the valve holds vacuum,the vsv is on the egr vacuum circuit,when running, the powered up vsv allows vacuum to source from the air cleaner box, preventing the egr from vacuum, if i pinch that line or unplug the vsv, the egr gets vacuum and operates, the ecm is holding the vsv open, as it would during warm up and at idle or wide open throttle.
 

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Discussion Starter #9
ect

followed it with the scanner, the temp was right in line with the ir temp, gun, the 50* startup-195*operating temp looked good, i thought the same thing, holding the egr till warmup, im still focusing on the ecm showing the wrong map, i guess ill go find a good ecm, i cant think of anything else that would dissallow the operation, outside the incorrect map reading, it just has to be too low
 

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If the egr test passes (implies passage ways are clean), and the vacuum modulator and vsv switch looks fine (T-line a vacuum gauge between vsv switch and egr valve input --> look for 2.0 - 5.0 in/Hg at an rpm other than idle ), check/replace the ECM. I wasted money replacing nearly every part related to the EGR system for my 96 Tercel, before switching out the ECM. Problem fixed. You can find these ECMs online -- ebay or car-part.com. Also they don't need to be reprogrammed at a dealer.
 

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ECM -- engine control module. Basically what Toyota calls the car's onboard computer. Other manufacturers will instead use the term ECU (engine control unit?). They both refer to the same thing.
 

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Got mines off ebay (~$50). Also visited the parts department at the Toyota dealership (California), but none in their network carry new ECMs. Car-part.com has them -- under the term "computer box engine" when you do a search on their website. And as you said, you might get lucky and find one at your local junkyard/pick-n-pull. Lastly, make sure you get the right model number of your ECM -- there's a sticker on it with the info.
 
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