Running Rich!

[S13srdave]

I have an S13 with a redtop sr swap, gt2871r, 73# msd injectors, Nismo FPR, 255 walbro pump, FMIC, z32 maf, for tuning, im using tunerpro 5 with a custom ROM tune. Tuning isn't the issue bc it was running fine on that tune before. My car has started running rich the last couple days. At idle, it sits at about 10.0:1-11.0:1 and stays in that range while under load as well. I haven't been able to find any boost leak, but tomorrow I'm taking my bumper off to double check my intercooler couplers. fuel pressure is sitting just over 40psi at idle. I've done a check on the injectors, they're not leaking. I do have a small exhaust leak, but its after my downpipe. You guys have any other ideas on what I can check?

[PyR0NiAk]

40 psi with the vacuum line hooked up?? It should be 42-44 with the vacuum line unhooked and capped...


Copied directly from the FAQ:
Fuel Pressure Regulators (FPR) are to be set to 43.5 psi with the vacuum source hose unplugged from it. With the hose plugged in, the regulator should read 36 psi. Aftermarket fuel pumps tend to force an old, tired regulator to run higher pressure. A Walbro 255 lph fuel pump has been shown to consistently run stock FPRs at 43 psi with their vacuum sources plugged in. This will result in a slightly rich condition, which doesn’t affect drivability or performance. It does seem to adversely affect injector life, however.

[DuckyD]

Also check your fuel injector o-rings.

[S13srdave]

Well, I got my fuel pressure reset, and I did find that the coupler coming off my turbo to the hot pipe was a little loose bc the clamp was failing, so I got a new clamp and it's nice and secure now. I also fixed the exhaust leak that I had. It runs better now, (big surprise) after fixing these issues but after its warmed up, I still have problems with it dropping down to around 10.0:1 at idle. I wondering if perhaps my coolant temp sensor or intake temp sensor are malfunctioning??

[DuckyD]

Well, I got my fuel pressure reset, and I did find that the coupler coming off my turbo to the hot pipe was a little loose bc the clamp was failing, so I got a new clamp and it's nice and secure now. I also fixed the exhaust leak that I had. It runs better now, (big surprise) after fixing these issues but after its warmed up, I still have problems with it dropping down to around 10.0:1 at idle. I wondering if perhaps my coolant temp sensor or intake temp sensor are malfunctioning??

I was about the suggest this.
If it starts getting funky once warmed up, check the ECU's coolant temp sensor.

[PyR0NiAk]

Well, I got my fuel pressure reset, and I did find that the coupler coming off my turbo to the hot pipe was a little loose bc the clamp was failing, so I got a new clamp and it's nice and secure now. I also fixed the exhaust leak that I had. It runs better now, (big surprise) after fixing these issues but after its warmed up, I still have problems with it dropping down to around 10.0:1 at idle. I wondering if perhaps my coolant temp sensor or intake temp sensor are malfunctioning??

If it starts getting funky once warmed up, check the ECU's coolant temp sensor.

I miss my WERD smiley

[S13srdave]

Well, I got my fuel pressure reset, and I did find that the coupler coming off my turbo to the hot pipe was a little loose bc the clamp was failing, so I got a new clamp and it's nice and secure now. I also fixed the exhaust leak that I had. It runs better now, (big surprise) after fixing these issues but after its warmed up, I still have problems with it dropping down to around 10.0:1 at idle. I wondering if perhaps my coolant temp sensor or intake temp sensor are malfunctioning??

I was about the suggest this.
If it starts getting funky once warmed up, check the ECU's coolant temp sensor.

Well it's not throwing a code, do you know how to check it otherwise?

[Second Shadow]

Coolant Temp Sensor:

to test your cts get an ohm meter and unplug the sensor and check the resitance of the sensor. you will also need a thermometer to check the temp of your coolant. the values are as follows:
Resistance 2.1 - 2.9 K ohms at 68 deg F
0.68 - 1.00 K ohms at 122 deg F
0.236 - 0.260 K ohms at 194 deg F

As this value decreases the computer increases fuel load and retards timing to lower cylinder head temps and reduce detonation.

[S13srdave]

Thanks for the help, I'll check it out.

[S13srdave]

Well guys, I thought it was my coolant temp sensor, so I ordered another one. Got it installed today, and now, I'm running ridiculously lean!

[S13srdave]

Nm, found that the vacuum line off my FPR had popped off. Runs a little rich at start up, but is running soo much better when it's warmed up!

[Second Shadow]

it's supposed to run a little rich at start up, once the CTS reads higher temps it leans it out to normal afr. which is why if it's bad and never reads the right temps, it never leans out.

gratz on fixing the problem man.

[S13srdave]

Ok, actually on start up, it's running lean as f*#k now and wants to die when I press on the gas. After about 8-10 mins driving around, it runs fine, actually really good.

[S13srdave]

I don't get it. It ran fine for about 2 days then after a couple hard pulls on it, it starts running rich as hell again! Like 10:1- 10:5 all the way through the powerband and at idle. I've gone over every vacuum line and can't find a leak! I disconnected my EBC and set it up running directly off the wastegate, and it's still rich! I've replace the plugs that had fouled out with some NGK Coppers gapped to .0025. That didn't fix it either. I starting to get really frustrated with this! Here's a list of things I've done trying to fix it, if you can think of anything else, let me know.
- Checked for boost/vacuum leaks, replaced the one that was leaking, helped but now its doing the same thing.
- Replaced coolant temp sensor, fixed the problem for about two days until i got vacuum leak see previous^^^^ If it burned up agian, what would have caused it?
- Checked for leaking injectors- not leaking
- Check ecu for codes, no codes
- any other ideas?

[PyR0NiAk]

Maybe a boost leak reappeared? What type of hose clamps are you using?

[S13srdave]

Maybe a boost leak reappeared? What type of hose clamps are you using?

On my Intercooler piping? T-bolt clamps like these, and they are all tight.

[PyR0NiAk]

How old are your couplers? Maybe one's got a hairline slit in it... Right after I finished my build, I developed a vacuum leak on 2nd start. It was a slit I couldn't even see but I was able to barely hear it. I replaced that coupler and no more vacuum leak.

[S13srdave]

How old are your couplers? Maybe one's got a hairline slit in it... Right after I finished my build, I developed a vacuum leak on 2nd start. It was a slit I couldn't even see but I was able to barely hear it. I replaced that coupler and no more vacuum leak.

I'm only using one older coupler that's about 2 years old, coming off my hotpipe to intercooler pipe on the driver's side, but I wasn't able to hear any leaks or see any noticeable cracks.

[S13srdave]

So today, I tried a couple different things, first found a small vacuum leak on the bottom of the manifold that I got plugged, that didn't resolve anything. I tried swapping my maf for a maf that I borrowed from a buddy that I know works, that didn't change anything. I then tried swapping his JWT ecu, as he has the same turbo and injectors I'm running, still no change, after a couple revs, the fuel ratio was still sitting at 10:0, but my boost gauge is reading a strong 16 lbs of vacuum . So then I decided to pull the fuel rail again to see if they had started leaking, which they weren't, but my buddy suggested trying to start it, to see what the fuel stream looked like. It looked as though the injectors weren't atomizing the fuel, but instead just shooting a stream of fuel. I bought them used and hadn't taken the time to have them flow tested as I should have. My friends going to loan me his 72# msd's and we'll see if that fixes anything.

[PyR0NiAk]

I hope this fixes it, buddy.

[S13srdave]

I hope this fixes it, buddy.

Me too! (crosses fingers)

[okinawa drift]

we are having the same problem! how much does it cost to flow test your injectors?

[PyR0NiAk]

Most rom tune services offer to flow test them for an additional price when they do your tune. It's less than $100. I know for a fact that JWT does it.

[S13srdave]

Here's an update guys- So I got ahold of another set of MSD 72#ers. I hooked them up and replaced spark plugs and it seemed to fix the problem. Running good, pulling hard all the way to 18lbs of boost! But as has happened before, after about 3 or four days of driving the car and it starts running rich again. I pulled the plugs out tonight and their caked. I really need to do a boost leak test, that has to be the problem. It takes a couple days to foul out the plugs. Any other ideas?

[S13srdave]

Bringing this one back from the dead!
Well, I was never able to find out what was causing the car to run rich. So the car sat for a loooong time not being used. Recently I replaced the rings (running so rich had fried mine), and while I had it out upgraded to a set of S3 cams from Jim wolf. Got everything reinstalled with a brand new harness from wiring specialties and guess what? It's still running rich, not at first but once the engine is warmed up, it sits between 10-11:1 afr at idle or while driving.
I found a crack in my downpipe, right by my O2 sensor and I've read that that might cause it to run rich (although I don't see it affecting it that bad.
So over the last two years I've replaced the-
coolant temp sensor (helped for about two days)
- tried swapping mafs from a friends car (no change)
- replaced an O2 sensor (no help)
- replaced my iavc (no help either)
- I'm also now running a Jim wolf ecu instead of that ROM tune I had, thinking it might have just been that tune.
I know I have a small vacuum leak somewhere right now, but that should lean me out at idle, not make it run richer.
Any other ideas?

[S13srdave]

Well today, replaced my coolant tempeture sensor again bc I couldn't get a good reading, and they're only like $16. Still no help...

[S13srdave]

UPDATE* Well since I've ha it back together, I've had a problem with the car running massively rich, like 10:1 ratio at idle, after it was warm. I replaced and tested a couple sensors like my coolant temperature sensor and throttle positioning sensor and haven't been able to figure it out. Well, I was reading through Dominski last night and got a couple ideas to try today.
1) check my ecu for codes
2) check my grounds
3) again, check for vacuum leaks

Well my ecu wasn't showing any codes so that didn't really help.
I checked for vacuum leaks and found a small one, that I repaired on site, helped a little.
I went to check my grounds and found one conning off my lower harness that I had missed, that was disconnected. Once I reconnected it, my afr leaned out. I took down the street for some gas and it's running just a bit lean now, lol. It's drivable though. I'm not going to boost on it, until I figure it out, but at least it's not dumping fuel anymore!

[S13srdave]

Pretty sure I found the problem. It was a voltage problem I was getting from my lower engine harness. Replaced it with a WS lower harness and it fixed it.

[compactfean]

What voltage problem are you referring too? There isn't really anything down there besides your main grounds that could affect anything.

[S13srdave]

Well at idle, when I turned on my electric fans, or heater, or headlights, my afr would increase. I took a short video - [youtube]http://m.youtube.com/watch?v=W27Kb_BVqLI[/youtube]

I figured it had to do something between my batter/alternator/harness and I had a new lower harness from wiring specialties so I installed it and it fixed the running rich problem. Actually, it's running a bit lean now between 16:1 and 17:1 at idle. I have to run my fans and ac/heater to push the afr back down between 14:5-15:5.
I still don't understand how the load from my accessories is affecting my afr.