x20dragon

Hey all new to the forums just looking for some feedback on if I'm thinking correctly and troubleshooting in the right order. Hope this isn't too long but wanted to include all the info I could.

Car is running rich at idle which goes less rich to normal as RPMs increase.

BLMs are around 112 to 120 at lower RPMs and even out to 128 on both banks at higher RPMs. BLMs are split with the right bank usually being 3 to 6 less than the left bank.

Relevant items replaced in the last year and a half: plugs, wires, optispark, fuel pump, fuel filter, ignition coil, EGR valve/solenoid, O2 sensors.

I tested fuel pressure from the schrader valve and here's what I get when testing:
Fuel pump primed (car off) : 44 PSI
Pressure after 30 min (car off): 37 PSI
Pressure after 60 min (car off): 21 PSI
Running (idle): 36 PSI
Running (FPR vacuum disconnected): 46 PSI

From my searching I think all the numbers I got are good. Only thing I'm not sure about is if the pressure should be decreasing that fast or if that's normal.

I'm leaning towards a slight leak in the fuel pressure regulator and/or leaky injectors. I did pull the vacuum line off the FPR and it has a faint fuel smell, however no liquid fuel in the vacuum line. I haven't pulled the rail yet to check for leaky injectors.

I attached a few logs as well if anyone wanted to look. They're in standard CSV format as well as in EEHack format which I've been using to scan. Appreciate any help!

hrcslam

If your sig is the complete list of all your mods, try disconnecting the MAF and see what happens. That should force SD mode (fueling without the MAF).

Also, a BLM split at idle usually points to the TB blades not being completely closed. Opening the .csv file in Excel shows the IAC counts are at 13. That's too low, and also points to the TB blades being opened at 0%. It's either that or a vacuum leak. But, a vacuum leak would cause a lean condition.

An exhaust leak can also cause a rich condition.

Your attachments wont open in EE Hack ("they appear to be corrupt"). When I open the .csv files in Scan9495, they don't show all the data and the graphs look like a 2 year old made it with a crayon. I'm not sure what happened there. LOL.

x20dragon

Thanks I'll try disconnecting the MAF and see what happens. I assume I'm looking for changes in the BLMs and just general idle feel?

Any easy way to check the TB blade position and adjust/fix if they're not fully closed?

EEHack changed the file format I think in version 4.5 so if you're opening those in an earlier version they won't open. The csv files I attached are just an export using EEHack.

I'll pull a scan with Scan9495 as well later this evening.

Thanks!

hrcslam

Yes, you're looking for BLMs closer to 128.

To check the TB blades, look at them with them closed. They should be completely closed.

FrankieD

iTrader: (9)

You should also address the issue of Knock Spark Retard. In some places it is as high as 10-11 degrees retard.(Highway speed about 1400-2400 rpm)

x20dragon

Unplugged the MAF last night and ran much better (logs attached). BLMs were still split but actually on the lean side now. Most of the time the left bank was around 131-134 and right bank was 128-131.

IAC at idle was the same (13 at idle; at the end of the log I let it idle for a bit).

Also no knock retard the entire run, but in SD mode both fans are on so maybe cooler engine eliminated that? I do have a 160 degree thermostat I could swap in to test. I have a 180 in there right now for the winter.

Possibly bad MAF? It is de-screened (did it years ago) which after some more research seems like a bad thing to do.

Will check TB blades today. Thanks!

x20dragon

Oh and since the question was asked, other mods include:

- descreened MAF
- TB airfoil
- LT4 knock module
- throttle body bypass

I'll update my sig -

BALLSS

x20

while you may have a leak or other problem going on....

your low IAC counts need to be addressed. Scan or use a DVM and see what TPS vdc are. they should be .67 (+/-) closed and 4.5 vdc full open. If you or someone f with the stop screw on the TB than adjust it so you get those vdc readings for TPS. If they check out otherwise, good

Low IAC counts are often because the stop screw was adjusted to open TB blades more at idle or the hole air passage in center of TB was enlarged to much by someone

If it is a stock TB and the hole in the center front of it has not been enlarged your IAC valve may be sticking or bad. You can remove it and use TB cleaner spray on it and orifice it goes into. Do not push or pull the end of the IAC valve or you will kill it.

hrcslam

That split isn't bad. But, the IAC counts are still low. I'd start with the TB blades.

Going to SD mode helping doesn't surprise me. You have a modified MAF on a modified air intake track. The MAF is calibrated to the plumbing it sits in with the screen in it, even just rotating the MAF effects it's calibration. You need to calibrate the MAF.

The good news is that the VE tables in that area are good. So you can calibrate the MAF only in that range.

Definitely leave it is SD mode and get good data logs of all BLM cells on EE Hack, run the analyzer, and adjust the VE tables accordingly. Once those are dialed in, reconnect the MAF and adjust the MAF calibration tables in the same manner. Once you get that dialed in, you'll have a very reliable tune.

I use Tuner PRO RT to adjust the tune and EE Hack for loading and logging.

x20dragon

Alright so after some diagnostics here's what I found:
TPS closed: 0.71V
TPS fully open: 4.58V
TPS reference (tan wire): 5.02V

I took the throttle body off, cleaned the MAF, IAC and IAC opening and the throttle body blades.

For what it's worth I checked resistance on the IAC and got 51.8 Ohms between pins C and D and 53.5 Ohms between pins A and B per this: http://shbox.com/1/iac2.jpg. Between pins A and D and B and C I got nothing so I believe that all checks out.

To my knowledge the throttle body stop screw hasn't been messed with, but before I put everything back together I backed it out a slight bit. After that I now get:

TPS closed: 0.67V
TPS open: 4.58V

Will capture some more logs today or tomorrow in both MAF and SD mode to see if there's any improvement in IAC counts, BLMs or idle feel.

hrcslam - appreciate the tuning advice. I've loaded a bin into Tuner Pro before but haven't messed with tables as of yet. I'll do some research and look into adjusting VE tables after running it in SD mode and then playing with the MAF tables after that. Thanks!

steveo_

that isn't 'running rich'. it's like 5% off target, well within the realm of reliable closed loop corrections, in fact i betcha if you scanned brand new off the showroom floor LT1s you'd find a few that were trimming 120 at low airflows.

5% additional fuel is not noticeable in normal driving, power, exhaust smell, fuel economy, or whatever, and closed loop is fixing it for you anyway.

the idle and low rpm blm split is probably due to your o2s being further back than stock, confusing the integrator, this is more pronounced at low RPMs, especially since mac mids place your o2 sensors at different distances from the exhaust ports.

in short, it sounds fine for a stock-ish car, and you're searching for problems where there aren't any. i'd almost leave it alone (in terms of fueling, anyway)

my hunch is your idle trims will get better if you close your throttle plates till they're damn near binding in the bores, and let the iac and the idle passages do their thing.

x20dragon

Thanks steveo - love your EEHack program and appreciate the reply. I agree this isn't a major problem and the car runs generally runs great, but wanted to make sure I wasn't missing anything.

I have some additional information after running a basic vacuum smoke test on the car - looks like I have 2 possible vacuum leaks.

Leak 1: Looks like I have a small leak from the driver side of the throttle body. Hard to see in the picture but smoke is coming from the spring/throttle linkage. Guessing I would have to replace the TB to fix as I don't believe that part is serviceable.

Leak 2: The center column in the EGR has an audible leak. Can someone confirm this isn't normal operation? I sprayed it with some water to make it more obvious and you can see what I'm talking about in this video:

Thoughts? Thanks!

hrcslam

I don't think the EGR leaking like that is normal. But, mine has been out of commission for a long time, so I cannot confirm.