Suddenly super lean while at cruise

**scheides** · 09-14-2005

Alright guys, I'm a bit stumped here.

Relivant info/mods:
2g w/ 6-bolt swap, maf-t in blow-through, 650cc FIC injectors, Whiney 255hp, SX FPR
Secondary info, prolly not exactly pertinant:
safc2, fmic, tial bov, ...etc.

Last week, a few days in a row, I was having a studder while at high-rpms while accellerating onto the freeway. After about the third time this happened, I realized I was low (less than 1/4 tank) on gas. I filled up, and the issue went away, straight away.

This weekend, several 20-30 minute drives, still having a bit of an overheating issue w/ my car w/ the ac on in the heavy heat, but other than that, nothing out of the ordinary.

Monday, I drive down to SE metro, and car starts to act funny while at a cruise on the freeway, around 70 mph. I put in the clutch, coast for a second, and it's gone. All of a sudden a moment later, it comes back again. This time, I'm watching all my gauges a bit more closely. Boost/Vacuum and EGT's are normal, but O2 (wideband) is going crazy, from 15.5-19.0:1. Very random.

I pop in the clutch, let the engine fall back to idle for a moment, then resume where I was, and the car drives fine for a bit. I can boost and rev through most of the rev range, but sometimes this condition will hit at high-rpm. Sometimes it will not. But otherwise, at a cruise, almost on queue now, it happens. I pop the clutch, re-engauge, and all is well for a bit.

So, I'm thinking it's something in the intake. Even though I have maf-t, I do a boost leak test from the throttle body elbow back. Voila, hissing from injector #2. I yank it out. Yippee! I've always been fond of FIC injectors until I heard about the shyte gaskets around each end of them. This one has had it. So, I yank all the injectors to swap in the stockers. Several others are not in good shape, so I'm thinking this is part of my problem. So, I reinstall the stockers, still with good condition o-rings, turn down maf-t to zero, turn down s-afc to zero, and turn down my MBC. Car starts and drives fine, then condition comes back.

After car is warm, I yank out the maf and do a boost leak test again. Oops, maybe those o-rings on the stock injectors aren't as good as I thought. I back off pressure on the fuel rail bolts a bit, re-seat the injectors, and then repeat. Seems to hold boost fine now, but guess what. I take the car for a drive, and yup, the issue returns!

MAF/MAF-T seems to read air correctly
Wideband sensor is relatively new, seems to operate correctly

I'm out of ideas for now, anyone else have any? I'll try and post more details as I remember them.

niterydr · 09-14-2005

My guess would be a fuel delivery issue? How is the regulator/pump/injectors? How do the spark plugs look?

**scheides** · 09-14-2005

Pump is six months old, and regulator seems to hold fine at idle ( and while setting base pressure) and swapping out injectors doesn't seem to change anything. I'm going to start with getting new o-rings/grommets for the injectors, I'm still suspicious there's a leak in there somewhere...

Matt D. · 09-14-2005

If you're concerned with it being a boost leak or the like wouldn't it be apparent at idle by lower than normal vacuum?

When you said your car sputtered by being low on gas and that putting more in fixed that problem my very first thought was that your fuel pump was damaged. They don't like being run dry at all one bit, and carltalon was suffering from the same problem recently I believe. Considering the car sputters at high RPM, and presumably full boost, I would only imagine that there is lack of fuel which to me would point to the fuel pump not doing it's job.

**scheides** · 09-14-2005

True, true.

Vacuum at idle is normal, vacuum while decelerating (even after the issue arises) is normal, and the car will boost fine for 2-4 pulls, and on the 3rd-5th it'll sputter at around 5-6k rpm. (pull as in drive around a bit, accellerate in second to 6k rpms, drive some more, accellerate in 3rd to 5-6k rpms, etc)

Where's carltalon on this? Now I'm curious about his experience. Speaking of carltalon, I actually got the injectors that are in the car from him....but, to reitterate, I swapped in the stockers last night, and the problem persists.

ps--10psi is boring.

**scheides** · 09-18-2005

Well well well. I found boost leaks around the FIC injectors I had installed and replaced them. Re-installed them & drove around & re-tuned a bit w/ my bro, and everything was fine. We stopped at subway on the way back and all of a sudden it starts running like shyte. We limp the car a few blocks back home and pop the hood. I had left the car running, and as soon as my brother lifted the hood it started to run fine.

Amazing. Mike from QPR made me a really, really nice bracket for my coilpack that mounts to my strut tower. I recently installed a strut tower brace and adjusted the mount a bit to make it all fit. When I did that, when the hood closed it would just touch the plastic covers that are on the back of the coilpack, where the wires mount to it.

DOH! Curious how consitant this problem was. Oh well, check make sure to check those connections!

slowbubblecar · 09-19-2005

I though james did that before you got it?(mount to strut tower)

**scheides** · 09-20-2005

he drilled some holes into the strut tower, and it looked like ass. Mike made me a proper mount for the whole coilpack.

**scheides** · 09-27-2005

Gah. I'm about to kick my car! The issue has re-arrisen. I re-did almost everything I did before, I had found more (small) boost leaks, and whatnot, I've checked a lot of electrical stuff, and now I've noticed this:

As this happens, my tach jumps around spurradically. Not much, but if I'm decellerating, then accellerate, as I accellerate the tach will jump up 150-300 rpms.

Anyone wanna join me in pointing my finger at the Cam Angle Sensor? I just replaced it with another one I got from jet just before the cookout...how often do these things go out?

**scheides** · 09-29-2005

SOB! Swapped out cam angle sensor tonight to no avail.

Anyone want to lend me their logger? I have beer...

blageo23 · 09-30-2005

I PM'd ya. Im free sunday if you wanna use my logger. Let me know.
Mike

Outlaw1 · 09-30-2005

Quote:

Originally Posted by scheides

As this happens, my tach jumps around spurradically. Not much, but if I'm decellerating, then accellerate, as I accellerate the tach will jump up 150-300 rpms.

A flickering tach is a tell tale sign of an ignition problem. Usually it's a bad wire but a bad coil will do the same thing. I'd swap another set of plug wires onto the car. I noticed the water sitting in the top of the strut tower. Was there water on the valve cover too? Look down in the spark plug holes and see if there's any sign of tracking on them. Not to say that's the only possibility, but that's where I'd start.

**scheides** · 10-01-2005

Thx for the advice! The water in the strut tower was b/c this pic was taken just before the all mitsu cookout, and I was doing a bit of cleaning under the hood (long before this all happened). The plug wires are almost brand new, 10mm taylors from elite. The #1 (shortest) plug wire actually had a minor manufacturing defect which I noticed after this was happening. The metal part that sticks into the coil for contact was only about half-way in (that's as far as it could go), and the tip of it was covered in carbon build-up. I adjusted the boot and it fits well now, but I did not clean off all of the carbon, as there was plenty of clean contact space left.

I swapped out to the original coils I had in the car w/ no change a few days ago.

I'll swap out the plug wire(s) & see if it helps.

btw, plug wells are dry.

**scheides** · 10-03-2005

Swapped out my nice 10mm taylor plug wires for my old magnacores, no luck. Checked out lots and lots of wiring, and everything seems to be ok, time for the multimeter...

I pulled the 'engine' link in the fuse box under the hood to reset the ecu, took it around the block. Seems to be worse, so I drove it a bit further to play w/ the afc & voila, car stumbles, stumbles, stumbles, and eventually dies. Now it won't start, and I'm officially happy to join the ranks of the undriveable dsm. It must miss it's native habitat on jackstands....

**scheides** · 11-20-2005

Who loves dsm's? I do!

After the car spent some time at LSE, it recieved a new CAS plug and fuel pressure regulator. Problem seemed to be resolved, and the car has run fine for two-three weeks. I'm finally planning on dumping money into more 'fun' stuff when voila! Back comes the problem!

I am thinking now that this has to be electrical some where, as the studdering a lot like running on 3 cylinders. Just to eliminate it, I swapped out the fuel pump for a brand-new Walbro 255HP today, no luck.

I am going to try and re-locate the coil-pack when I get back from vacation. With the coil pack near the hood like it is, I had one other incident where one of the boots of the wires coming off of one of the coils actually was burnt through in one spot, grounding out at idle.

Any other ideas? Anyone want to help? Cash reward for anyone who solves this for me. I've wasted too many hours and too much money already, and 70+ hour work weeks make me not want to do anything when I'm not working

I'll be out of town until 11.29. If anyone can/wants to help me anytime after that, let me know. I'm serious about the cash.

93sc · 11-20-2005

How's your alternator doing? What does the voltage look like when the problem seems to surface?

EclipseGST · 11-21-2005

My car was doing the same thing this last week, took out the plugs, cleaned them up a bit and regapped them and it worked just fine. Now its doing it again so I am just going to swap them out. If that doesnt work then I will have to search farther.

Have you tried a new power transister or running a ground strap from it to the firewall? I remember I had a problem like this before where it would only run on the 2nd and 3rd cylinder and it was because the transister wasnt grounded good enough. I'd check that and also make sure its got a good connection with the harness. If you dont know what I am talking about, its the little black box located near your FPR and where the coil pack mounts on the intake manifold.

Hope it helps.

**scheides** · 11-21-2005

Good question. Voltage is rock solid during the condition ~14.1v.

Also, I've thought that maybe it was the CAS going bad (mentioned above) but while looking at my safc during the condition, it stays rock solid, as does my MAF--no major oscillations that would seem to cause this issue. I replaced the CAS anyways, to no avail.

Here's a trick, though: as I mentioned above, sometimes my tach seems to jump up and down a bit during the condition. However, if I look at the afc, it reads steady. The s-afc is spliced into the ecu harness, but I hardly see how this could be the cause (it seems more likely that the lead going to the ecu would be dead, not just consistantly messed up under specific conditions : 10-15% throttle at cruise, near 3000 rpm).

**scheides** · 11-21-2005

EclipseGST: thanks man, I'll try these too.

Remember though, this happens ONLY at partial throttle (10-15%) while cruising in any gear around 3000+ rpms. I can run through the gears to redline at full or part throttle (50% ++ or whatever) and the car drives great, no lean condition on wideband. no oil leaks, no fluid leaks.

EclipseGST · 11-21-2005

Have you messed with the TPS at all?