Could I just unplug the line , an then unplug the pig tail to the solenoid? sense it is deffinitly closed. Won't that do the same thing as capping it off sense its disconect the pigtail. Then it won't be able to open? Or would that set an engine light ? I don't have any vac caps. An any store is 20 minutes away and its getting late. I'm hoping disconeting the line AN the pigtail and then resetting the battery will fix this issue for the next day or two. If it works. I will replace the solinoid. Also hoping it fixes my wonky fuel trims. I thought I remember Stanina mae a thread about how disconecting his evap fixed his fuel trims ?

 

I'm going to disconnect the pigtail to the solinoid but leave the line plugged into it. And then disconnect the battery and see whar happens. Just for a day or so. If my fuel trims stabilize and my afr stabilize I will be a happy camper. Fingers crossed.....

 

Well that didn't work out to well. I disconected the conecter to the solenoid. And reset the battery. Wow...my car turned more or less gutless. No where near the power. Its pouring out and at wot in second gear it won't even spin at all. That's pretty bad for a Gms1 car to not break loose in second gear in the pouring rain. And mynktft frooze at 0.... and my St ft where all over the place. From +9 to -15. So I reconnected my solenoid and the ecu again. With in 5 or 6 miles of driving I am back at -4.1 ltft already. My stft bounce from +9 to -15 still. And the car is pissing me off now. My AFR commanded is 14.7. Bug the measured flux around 15.8 to 12.9 is. Once or twice on desel after I came into it and let off I saw both AFR readings goto 29.9. Oh Lord my car is messed up. Between not starting right in the mornjng s and my crazy fuel trims.

 

No you cannot just unplug the connector. You leave that plugged in but unplug and cap the nipple on top. Unplugging the connector just leaves it stuck open or closed.

 

I am kinda lost as to what the problem is. Lol... I am correct in thinking I might have two problems ? One being a bad our he valve. And then other being some sort of possible boost leak ? Where shold start? Replace the solenoid and boost leak test the car..? And in your experience. Where I can't blow through the solenoid. Should I replace it or the one at the tank. The p0490 says low purge flow. Or would a boost leak cause my stall issue too and bad fuel trims.

 

Start by capping the purge valve off to see if it fixes the issues. If it does you have no boost leaks and you likely need just the new purge solenoid. If the fuel trims are still way off then time to do a boost leak test. The cap test costs almost nothing and takes 2 minutes or less to do.

 

I will be picking up a vac cap today and caping it off to see what happens with my fuel trims. This morning on the way to work they dropped aagin from the -4.1 it was last to -7.2 by the time i got to work. And my drive to work is a 15 minute highway drive. No stop and go traffic at all.

But , I think I might have a hpfp problem causing my stall issue at cold start ? I only say that because this morning when I started my car it started up perfect and ran with no problems at all. Not even a sputter. And I noticed for the first 10 to 15 seconds when the car first started my fuel rail pressure was up at about 1700 ish psi. And the car ran great. I have caught a kwick glimpse of my fuel rail pressure on the days my car stalls and the fuel rail pressure was around 400-600psi when the car would first start and then stall.

Does anyone know for sure what the fuel pressure should be on cold start after sitting for about 6-8 hours for the first 10 to 20 seconds of the car being started. If anyone has a way like torque or an rpd to measure it. Please confirm the rail pressure on cold start plesae ! A video would be great. I would love to compare it to my car. I might have a hpfp issue. Or regulator issue. Could that cause my wierd fuel trims also ? I don't mean to waste anyones time. I just really want to get this car fixed and get the right parts. I'm only shooting at the hpfp now because of the extreme difference in rail pressure each day.

Thanks everyone !

 

I would really like termi to chime in on this because I'm far from an expert. I just ran Torque on a cold start. 1600 initial psi and then dropped to about 1100 till it was warm.

With that being said, and I could be wrong, if you are having an evap issue, it will cause a drop in pressure.

If it were me, with my personal experience, i would fix the evap issue before you move to something more serious like a hpfp issue. You will beat yourself up if it's just the purge valve.

With that being said, I'm not sure what your money situation is and I know throwing parts at stuff is not an easy thing to chew, but our cars are known for evap purge selenoid failure and we generally advise to start there. Then move to Vent valve by the tank if that doesnt' fix it.

 

That is about right on the stock tune on cold start cat heating mode.

 

First off , let me say I appreciate EVERYONES help and paitenice on this thred/issue. If trem does read this. Which he has been great at for me. I am really curious about the rail pressure alos. My car started and ran perfect this morning. And the feul rail read a good 1600-1700+ psi for abit untill it idled down normally. On the mornings that it stalled. My rail pressure was at 400-600 psi MAX. ( But I thought that was normal intill this morning ) so I never thought anything of it. I would be really interested to find out IF and HOW a bad purge or vent valve could cause my rail pressure to drop almost 1000+ psi ? I'm not doubting anyone. I just want to understand whats going on with my car. If it indeed can cause fuel rail drops then I will buy a new purge TONIGHT !! Money is tight for myself right now. Thats the only reason I am trying to make sure 100% what is wrong. I work in construction. And with the economy the way it is so slow. My hours have been cut back a fair amount. I can swing a new purge. Just not the purge, and then realize , Oh...its actually the vent valve . Or the hpfp ! I will pateintly await and see what term syas about cold start fuel rail pressure and where it shoud be and if it could cause a drastic drop in rail pressure with a bad purge causing my stall issue. But I still want to piont out. I use to hear my vent valve open and close from time to time. I havnt in some time now. So I may have to go ahead and replace both the purge nd vent valve to be sure.

 

Would that be the same for a gms1 car to have about 1600+ psi on cold start ? and would a bad purge cause a drop in rail pressure from the hpfp causing my stalling issue ? Cause when my car stalls , my rail pressure is around 400-600 psi on cold start up. And then I still dont get an engine light. But in torque I can see a code for a p0490 fault code ( Evap low flow ) .

 

Yes it could be flooding the engine out with gas vapors and since the HPFP is cam driven when the motor stumbles the fuel pressure drops badly.

 

If the purge valve is bad i assume it's like having a vacuum leak and would cause all kinds of issues like pressure drops etc.

If you really want to try and test this and can't cap the line, then try this. Reset fuel trims. Probably easier to do with a battery pull. After you reconnect the battery cable, go and disconnect the electrical connector on the Evap Purge Valve on the intake manifold. If your issues go away then you will likely know it's bad.

This will probably set a code if driven like this for long. It doesn't hurt anything and is a good free way to test for failure.

 

He already did this and the car ran even worse.

 

**** I missed that part.

 

I'm gonna head to the realer tonight and pick up a purge valve and a vent valve.. so I hope they fix my problem . I'll let ya know

 

Im gonna punch my car in its ecu. I'm on my way to the dealer to get the purge valve and vent valve. And on the way to the dealer my ltft continues to drop to almost -10%. I go into the dealer and buy the parts. Start driving home and of course. My ltft starts to level out and raises from -10% to about a decent -3.1%. Or at least a 3% is way better then what they have been lately. So I changed the two parts. I'm gonna jump out on a limb and assume it was the vent valve in the trunk. I don't think its suppose to rattle around like a fun can of marbles when you lightly shake it. Cause the new one doesn't make a sound. My old one sounds broken. I will try to take a video. But seriously. Im punching my lnf in its ecu if this doesn't fix it ! I will know soon once I re connect the battery and drive for a few miles. The old one really sounded like it had loose parts in it.

 

maybe a broken plunger in that. any luck?

 

I'm still waiting to get a few miles on it... bit ago far after the drive to work today. I'm looking at about a -4 to -5% ltft. Its still way better then the -9.8% ltft I was running. I'm starting to wonder of that's just how my car wants to run with the stock air box and gms1. Or if I do have a leak where it is pulling in air under vacuum. I'm going to boost leak test it soon. If it doesn't have a leak. Then I'm really lost. Any thoughts ?

 

Small leak most likely by the map sensor on the lower charge pipe or at one of the couplers on your injen hot pipe.

 

I hope it is a small leak in one of the couplers from the injen side. The cold pipe is still stock. And if it is leaking out around the lower map. That looks hard to get at and fix.what would cause them to leak ?

 

So are you still have cold start issues? Wild fluctuations in fuel trims?

 

Bad, damaged during install, or wrong size o-ring on the map sensors. Also the GMS1 3 bar maps have only one bolt not two and they often sit crooked in order to get the bolt to line up properly.

 

That sounds like it might be hard to fix if it is leaking at the either of the map sensors. I'm gonna pray its a bad seal on the silicone coupler that has blown the injen off a few times. I'll order the mpx upgraded couplers and clamps from modern performance and re test for leaks. Hard to think that a small leak could throw fuels trims out that bad. Once I get this sorted oot I can finally get u to tune the car.

 

subd!

i think im having the same cold start issue! starts up and them sounds like it has a cam in it then stumbles and stumble and then finally the idle jumps up to around 1500RPM and then it settles at 1200RPM during the warm up cycle.

it did it to me twice today. what is the vent valve in the trunk you speak of? i know the purge valve on the top of the intake mani has been known for problems.