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Car Randomly Going Lean

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StrokerMax

Proven Member
161
11
Mar 27, 2014
Colorado Spring, Colorado
Hey Guys,

I am looking for some help with a problem I'm having. I've only ran the car 20 miles since my motor rebuild and today the car randomly started running super lean on my wideband. Car felt like it was misfiring so I popped it in neutral and the car stalled.

Popped the hood and noticed my fuel pressure gauge on my aeromotive fuel pressure regulator was maxed out.

The car wouldn't start... Then after about 10 minutes of sitting it started. I drove home very slow but it continued to spike lean on and off. (I was only about a 1/4 mile from home).


Just to give you some background: I purchased the car out of state and it turned out to have been build by someone who did a hack job. I rebuilt the motor then had my tranny blow a few miles later. Had it built by Jacks.

My car has:

6 Bolt swap with a stroker
2150cc FIC injectors
Walbro 255 (I have a 450 that is on my list to install shortly)
Stainless sending and return lines
Aeromotive Fuel pressure regulator
Replaced my Fuelab fuel filter when I rebuilt the motor... It was all gummed up

This issue is something that has happened since the rebuild... Like I say I've only put about 20 miles on the new motor. My old wideband wasn't working right so I just replaced it with an Autometer Wideband. Now I could see the car leaning out and I can feel it loosing power.

Any help with troubleshooting is greatly appreciated. This car has given me a lot of trouble but I'm determined to get it running 100%
 
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My old fuel pressure regulator gauge was bad so I replaced it. But there could be a chance that something is causing the gauge to read incorrectly again. I did notice that the gauge was reading pressure after the car had sat overnight as well.
 
the first thing i would do is adjust your base fuel pressure. the problem you are describing sounds more like a flooded engine than a lean one ( gauge maxed, car had to sit before started). Is it lean all the time, or just here and there throughout the rpms?
 
I know my baseline fuel pressure was set correctly before my first gauge froze. I just never double checked it after putting on the new gauge. I'll start there... I won't be able to play with it until tomorrow because we are out of town today.

The car is going lean here and there through the RPM's. I had it pretty dialed in with ECU Link to idle at 14.2.... Then it randomly started shooting up really lean so I added more fuel but it still kept doing it. As I would be driving I would be at 12-14.2 then bam it shoots to 16 or 17 and comes back down. I had a few times that it was going really rich too then bouncing back to really lean. Then sometimes it would start sticking at 17 so I would let off. When it stuck at lean the car ran like it was mis-firing.

I thought I might have had bad gas... The gas in the tank may have been in there for years for all I know. But I filled it up at the gas station right down the road and that didn't help at all.
 
I ended up ordering a new Aeromotive Fuel pressure gauge. I think my current one has an issue. It was already sticking. Once I get the new one in I will make sure my baseline pressure is correctly adjusted. Hope thats my issue.

I tried cleaning my MAF and also replaced my throttle position sensor. For some reason my TPS isn't data logging in ECU link. None of those made a difference with the fuel issue and my TPS still doesn't log.

I'm pulling a 0443 EVAP Emission control system purge valve c fault. Not sure that could be related or not.

I'll update the forum once I get my fuel pressure gauge on later this week.
 
Okay Guys... I still need some help with this one.

I put on my new fuel pressure gauge and my baseline pressure was fine. Right about 43PSI at idle

I did a boost leak down test again and found a wicked crack in my intercooler. Got that welded up and put back on. It sure helped my car to idle smoother and seems to have helped my lean issue a little but its still there.

My car is having a problem jumping from rich to lean. It seems to lean out more when I start using more of the pedal. I'm afraid to drive it too much. I was just lightly accelerating down the road today and it was going from 10.5 - 11 then maxing at 16+ AFR. It didn't stall this time at least.

I have the 2150cc FIC injectors and unfortunately my car only has ECU link version 1.

Is it possible that my fuel pump could cause this? Maybes its worth putting on my Walboro 450 to see if it helps? Or is my fuel trim not set correctly? I used the calculator and my Global fuel is -79.3 and deadtime is 350. Sorry I'm a noob at tunning and have been trying to learn more as I go.


Thanks for you help
 
I don't know if DSMLink V1 has the DTC feature/Tab if so what are the codes?
Man, sorry if I'm not posting helpful info right now but I do have the same issue as you! Mine is little more extreme tho When I push the gas pedal it would go so lean that jerks in the 19.x-20.x range and some times is the exact oposite it would go so rich tha starts missfiring.
One thing I did notice is that the AirFlowPerRev goes way out of its "normal" range for example it supposed to be .25-.26 at idle (stock cams, 2.0L) and mine was at .75 or so and my vacuum was very low
I'm on SD and 750cc injectors 43psi base fuel pressure... I don't know if the above help you or at least gave a starting point, two brains think better than one I help you, you help me... :thumb:
 
The only two DTC's I've seen pop up are 0043 (Evap Purge control) I'm pretty sure my car doesn't even have the purge valve. My fuel system is totally aftermarket. Stainless lines with no stock parts.

I'm also getting 0141 which is for the rear 02 sensor. I am going to send in my ECU Link in for an upgrade to V3 but I don't want to put my car down right now.

Two heads are for sure better than one! Thank you for your help. This is a hard issue to track down.

I've read every thread I can find with this issue. Do you have an aftermarket MAF? I read a thread that a guy had his MAF Comp settings wrong. http://www.dsmtuners.com/threads/car-randomly-goes-lean.373674/

I'm not sure mine is stock or not. I lean to say its not. Maybe this is my issue too.

I'm not sure how to check my airflow per rev with V1. All the new tutorials on tunning are with V3. HAHA.
 
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I don't have a MAF I use SD (speed density) I don't know about you and what MAF does v1 support but either could be an evo MAF a 3rd gen eclipse MAF or the stock 2g MAF. Have you tried the video tutorials in ECMtuning.com. I want to think my issue is lack of tune instead of mechanical problem. What I did a couple days ago and the problem "kinda" stopped is, I cleaned al air related sensors. I used contact cleaner and a toothbrush LOL and it's been better since then. If I find something else I let you know.
 
I think my issue is also tunning related rather than mechanical. Who knows. This car has given me a hard time but it's close.

I'm going to watch a few more of those tutorials and see if I can get it dialed in. The hard part is learning V3 and then going back to V1 that is missing features.

Keep me posted on your issue.
 
Can anyone look at my data log for me please? I don't know the first thing other than setting up basic fuel trim.

My car is still jumping lean. I just took it out and noticed its only going super lean on the downshift (16+). At partial throttle it stays at or below 14-15. However I tried easing into the throttle a little more and it backfired.

Then after running it a mile it spiked lean and stalled. I waited 10 minutes and then it fired back up. Made me wonder if the Fuel pump is going bad. So strange
 

Attachments

  • log.2014.07.10-01.elg
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Damn man! It's kinda messed up I don't know if with V1 you can log other stuff than the one you have logged but you are missing important data like the MAF, combined FT, throttle volts(TPS), ISC, etc.
The coolant temp is essential for closed loop operation! you should remove the cauge temp sensor the one with one wire instead of the one under it with the 2 wires. Also your car is in constant open loop! You need to spend some under the hood time and fix those issues also get a V3 is good upgrade at this point!
 
Thanks for taking a look. I didn't know that about the coolant temp. I will wire the stock set-up back in. My gauge doesn't work so I got an autometer water temp gauge. but then the stock sensor doesn't plug in. That could be a good part of my problem right there. I'll try that and run it again to see if it hits closed loop.

Yeah I cannot add the MAF, Combined FT, or TPS with V1. Might be time to upgrade or I'll be stuck chasing my tail.

Got my Walboro 450 in but that didn't make any difference. It does idle smoother though.
 
Do you have the ect sensor that the Ecu needs to make sure the car starts and goes into closed loop? The coolant guage sensor isn't a big deal but the Ecu one is.
 
I know the sensor is there but I'm not sure its hooked up right. I'll check it later this morning.

This car has a bunch of un-hooked plugs due to so many aftermarket parts. I'm wondering if that is the source of my problem. Something isn't plugged in which is keeping the car in open loop 24/7 and causing the AFR to go crazy.

Thank you for your help!
 
Okay. I made sure my ECT is all hooked up right and took my car around the block.... NO luck. Its still going lean and stuck in open loop. It goes lean the worst on downshift with a load on the motor (no throttle).

After about 5-8 minutes of operation it dies and won't start for 15 minutes.

Do you guys think my front O2 is bad? Or could my rear O2 being disconnected cause this issue?
 
Ok. Rear o2 won't affect your fuel trims at all.
Front o2 from the log it seems is doing its job! It just doesn't cycle at all (stock in open loop)
And going lean with load and no throttle (let off the throttle with gear in) is perfectly normal. Going lean while on throttle is the bad thing!
The thing that it dies and won't start after it cools down it might be the power transistor unit! Search it up...
I would recommend you to look for leaks exhaust leaks (pre o2 leaks).
 
Good to know that being lean with load and no throttle is normal...:thumb:. I didn't get out and give it much throttle but it didn't seam to be leaning out like before. That ECT might have helped. That and I could see an exhaust leak causing some problems with my wideband. I may not have aligned my downpipe 100% right when I rebuilt the tranny. I'll check that tomorrow and look for Pre-02 leaks as well.

You might be 100% right on the Transistor unit! I was just reading about others that had a bad transistor and the car not running right when hot. Its cheap enough that I will just replace it and see what happens. Hope I can track one down in town tomorrow.

When my problem
initially happened it kind of acted like a misfire or that it was running on 2 cylinders or something. It was stuttering, going lean, and loosing all power. I thought about coil packs but never thought about the transistor.

I'll let you guys know what happens. Thank you
 
Look let me reiterate what I wrote above about the lean thing before someone chime in and flame me.
Yes is normal! When in gear and you let of the throttle it will go rich for a sec or two and then the ECU guts fuel (goes lean) until the rpm get low enough then start to inject fuel again to keep it form stalling.
 
Well no luck. I changed the Ignition Control Module (Power transistor). The 02 actually cycled at idle for about 60 seconds then stopped.... Took it down the street and ran just fine for a few minutes. Then on the way back the RPMS dropped to zero while I was still in gear rolling. Popped it in neutral and the car stalled. Sat there for about 20 minutes before it fired up and I drove it up my street. But it kept loosing power and almost stalling. My fuel pressure looks pretty consistent.

Figured what the heck... Might as well try the new 02 sensor. I just started the car and let it run up to at least 190 degrees. The sensor does not cycle. Just stays at .88 -.90 v.

I'm stumped. :confused: The prior owner of this car hacked so many things that I have no idea.

New walboro 450 Fuel pump
New NGK wires
New Spark plugs
New power transistor
New 02 Sensor
Fixed all boost leaks
re-aligned my downpipe and cheked my exhaust manifold

Still remaining potential:

- Bad coil pack
- Bad ECU
- Poor tunning due to V1 DSM Link (But should be able to get the car to drive a little with V1).
- My multi meter isn't working so I didn't check my Voltage at the O2 plug. But its working according to link.
- Some type of disconnected sensor???

OBD II readiness Shows:
Catalyst - Incomplete
Oxygen Sensor - Incomplete
Oxygen Sensor Heater - Completed
EGR System Incomplete
 
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