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2G Running very lean, high idle & not building boost

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AZDSM

15+ Year Contributor
80
5
Sep 1, 2006
Fort Hood, Texas
So when I first bought this car last year around May, it drove home fine. Built boost and pulled hard. I pretty much tore it down from there as I saw a lot of crap I wanted to replace I wasn't ok with. Compression test last July came back good. It's a 2.3 stroker, but numbers were 160 across the board. Skip to summer this year is when I finally got around to getting things worked out with a few parts and was able to fire her up. Everything sounded and looked good, but it obviously wasn't.

When I first start it up from a cold start, AFR will look good, but after about a minute will dip into 15-16 area and pretty much stay there. Idle as of now is around 1600rpm. Now it would sound like it is a bad boost leak and from everything I've read, would agree. My boost gauge sits at about 15 vacuum on idle and when I give it any amount of throttle it will go to 0, but no more. The BOV makes a slight whirring sound. BOV worked fine last year before I tore the car apart.

- I've replaced a lot of gaskets. Turbo, j-pipe, both throttle, BOV.
- Fixed boost leaks at throttle gasket areas.
- Replaced BISS screw as it was leaking
- Vacuum hoses on TB were leaking. Fixed that.
- Replaced throttle cable with non-cruise cable as it wasn't allowing the throttle plate to close fully.
- Upper intercooler pipe going into TB was cracked. Had it welded.
- Fixed TPS sensor. Verified good through resistance check.
- Replaced IPS, verified good resistance as well.
- Wastegate DOES work. I've forced compressed air into the line to verify the flapper opens. It just doesn't do anything with any amount of load/throttle.
- Turbo is good. Even pulled it to check hotside.
- No blockage in exhaust.
- Power resistor is good.
- Injector resistance pack is good
- Coil packs are good, although one read high than what spec calls for (never got a yes/no if it should be replaced or not since it's not dead)

I've fixed so many boost leaks I honestly don't know what else to check at this point. Now admittedly, the boost leak tester I have isn't perfect. It does leak itself (LOL..). I need to epoxy it and seal it so I can test my engine can hold the boost. But outside of that, I honestly don't know what to look for at this point. I can only think maybe the EGR is stuck open or my intercooler is seriously cracked somewhere not visually obvious with a spray bottle.

I need some ideas on what to do from here. Here is a pic of what I am working with.

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Work backwards from the head to the turbo. I'd start with a boost leak test again with it at the TB elbow. Most obvious ones would be intake manifold to head gasket, TB to intake manifold gasket, and TB elbow to TB gasket. Another one would be the BISS. Make sure the O-ring is in there. ISC also has an o-ring. Check TB shaft seals. And don't just check what you can see from the top. You might be leaking underneath the manifold or TB. Also did you set base timing?

After that, if it checks out okay, move further down to the turbo, including one other major component at a time. The BOV would be one segment, then the intercooler, and finally to the turbo.
 
Work backwards from the head to the turbo. I'd start with a boost leak test again with it at the TB elbow. Most obvious ones would be intake manifold to head gasket, TB to intake manifold gasket, and TB elbow to TB gasket. Another one would be the BISS. Make sure the O-ring is in there. ISC also has an o-ring. Check TB shaft seals. And don't just check what you can see from the top. You might be leaking underneath the manifold or TB. Also did you set base timing?

After that, if it checks out okay, move further down to the turbo, including one other major component at a time. The BOV would be one segment, then the intercooler, and finally to the turbo.
Thanks for the response. A few things you mentioned I wanted to clarify on.

Both throttle body gaskets are new and replaced. No leaks(had one at TB elbow/TB gasket before). BISS screw is new as is the o-ring inside of it. It no longer leaks. ISC o-ring was present and in good condition.

Is there an easy way to check the TB shaft seals without tearing the whole thing apart?

Also, no on base timing. That's one thing I'm not familiar with at all.
 
If I'm not mistaken your info sounds like normal, you wont build boost just by revving the engine. Engines will run lean idling, there is no fear of the engine detonating without any load. As far as the 1600 rpm idle, all you should need to do is set your base timing and adjust your BISS.
 
Didn't realize this topic was so old now, but I do have a few updates. (still not building boost)

- TB shaft seal was leaking. Took me a while to get that all fixed since the screws were a pita. But shaft seals are replaced.
- Took the liberty of removing the EGR and installed a block off plate. Capped off TB vacuum nozzles.
- At the time(a few months ago) the shaft seal was the only boost leak I could find that was remaining. Otherwise my system seems rock solid. Even tested the IC itself and it held 15 psi for 10+ minutes. Do need to retest it again though after replacing the shaft seals.

Have you changed the fuel filter.
Yes. It was one of the first things I did.

Pressurize it and take off the TPS sensor and spray some soapy water on the sides.
Didn't do this to find the leak, but I had my g/f hold the nozzle onto the BLT to supply a constant charge. Could hear it hissing and felt the air from around the springs.

Oddly enough, I'm extremely hesitant thinking the shaft seal that goes on the outside will stay in place. When I was putting the shaft back in, the seals popped out a few times as I kept trying to align it to get the plate back in. I did have de-electric grease on the shaft/seals to make it easier to install so maybe that was just the issue... but my thought is the seal behind the TPS is snug and can't move because of the plastic guard/metal plate. But the seal on the cable side seems to be in open air and I don't see anything stopping it from popping out under boost. Are my suspicions me being too cautious or is this a potential problem?

Do you have a blocked of FIAV?
No. FIAV is still there.

If I'm not mistaken your info sounds like normal, you wont build boost just by revving the engine. Engines will run lean idling, there is no fear of the engine detonating without any load. As far as the 1600 rpm idle, all you should need to do is set your base timing and adjust your BISS.
I'm not sure about this... I'm almost sure this isn't true. The car built boost and the BOV worked fine anytime I revved it in idle while driving it home. (although you have me second guessing myself now, ha..)

check your fuel pressure.
This is the next thing on my list. I've been waiting for a good deal on an AFPR as I do think my pressure is off and it is pushing too much fuel into the chambers. (I do have a wally 255 pump)

ps - sorry if thread revival is against the rules(haven't checked). But the thread is still relevant as the issues are persistant.
 
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Can you post a log? I'd like to look at your settings. What injectors do you have?
Wish I could, but I don't have DSM Link or anything fancy to tune with. Car had a weird list of mods when I got it. Stock blue top injectors btw.

Couldn't edit the main post(suppose since it's so old now) to supply some minor details about add-ons and what have you. But here is a basic break down.

- 2.3 stroker(bottom end components are unknown), head is stock. Less than 5k on rebuild
- ebay 16g with 5k on it
- VRSF short run IC
- Greddy Type S BOV
- internal wastegate
- 3" no name exhaust full back
- 1g throttle body
- stock blue top injectors
- stock FPR
- walbro 255 pump

I do have a boost gauge, EGT and AEM A/F, but it has stopped working recently. Think the O2 is shot since it's stuck at 14.8 and nothing is unplugged from the back.

I do have a bluetooth OBD2 scanner I use to check codes and crap, but I'm not sure if any help it could be for more data on logs and settings you're requesting.
 
Hmm, if the stock FPR was being overrun the car would be running really rich, not lean. Is the MAF plugged in/working? With it being a 2.3 i really wouldnt run any more than wastegate pressure until you have some way to tune. At this point I'd say Link, blackbox or standalone are really your only viable options, because the load scale will be wrong for a stroker using 2.0 tables.
 
Hmm, if the stock FPR was being overrun the car would be running really rich, not lean. Is the MAF plugged in/working? With it being a 2.3 i really wouldnt run any more than wastegate pressure until you have some way to tune. At this point I'd say Link, blackbox or standalone are really your only viable options, because the load scale will be wrong for a stroker using 2.0 tables.

I would agree with this, but I also can't figure out why there is so much... condensation? Or something that spits out the exhaust pipe. It used to be black like soot, but that was when I first got it running after a year of sitting. Now it is just clear. Doesn't smell like anything. But it leaves a visable trail on the garage floor after I cut it off.

I am content with WG pressure at this point. I just want the stupid thing to boost again. I really have no idea what to look for at this point.

It will be a while until I can afford Link. Not sure if it is worth mentioning that my plugs are BPR7's. I've been debating whether I should try 6's or not. (I don't expect this to be my boost problem at all, but whatevs).

edit: Yes, MAF works fine. I've tested it one too many times in the past, LOL.
 
I'll check it out.

After doing some reading, I read it is best to use 6's for mostly stock/under 15 psi and 7's for higher HP applications. So I've opted to get 6's tomorrow to replace my 7's. In the mean time, I pulled the 7's and this is what they look like. Mind you, the car pretty much sits 24/7 in the garage and I fire it up once a week/month depending on whats pulled at the time. So they are basically brand new.

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EDIT: nvm, didn't realize this is what 1g CTS looked like. Something to note, I don't ever have issues firing her up. No hesitation at all, etc. I'm reading this is common if the CTS is jacked up. But I suppose it could be "off" without throwing a CEL like you're saying?

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Well if you only run it for a short time it may not throw a code. Also the 1g and 2g sensor may be different, I'm not really sure. I used all sensors that went with my engine apart from the cam sensor when I did my swap, and I'll use the 2g cam sensor again when I get a threaded intake cam. Oh and at least on my previous stock 2g, I ran 7 plugs and it was always fine. This one which is heavily modified also runs 7's, and i've had no spark issues. I did have an occasional miss at idle (like it'd happen once a week) that seems to just have been the voltage based deadtime curve. And just be sure to get something to tune soon. I'm not sure if the blackbox can modify load scale, but it's pretty necessary for more than stock displacement. An SAFC or MAF translator would technically work, just not very well considering how far your VE is from stock.
 
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