Codes 1171, 0137, 0157 SOLVED

I've been triggering these codes, and setting the CEL ever since I installed the supercharger. In the past, its been that the nut for the EGR had come loose. These codes are for low O2 voltage, and low MAS readings.

This past week the codes have been coming on more and more frequently, today coming on every time I gave it more than half throttle. The engine had no power, and felt like the ECU was pulling timing. I travel with a 22mm open end wrench to constantly tighten the nut, but this wasn't the solution.

These codes imply a lean condition. This had to be a leak somewhere after the MAS, and before the supercharger. The engine was taking in extra unmetered air, and not getting the fuel it needed for it.

When I arrived home today I pulled the intake, and found the cause. The intake air sensor was loose in the intake elbow.

The reason for this is the location of the sensor. The sensor needs to be moved back slightly to take the strain off of the harness. As it is now the harness needs to be unwouond back to even plug this sensor in at all.

I will be making a complete new intake these holiday weekends, and will post completed pics, and material sources.

John C.

ARRRRGH! its back! The codes have returned.

OK, so today I replaced the fuel filter, pcv, and all the vac hoses.

I went out for a blast, and hit the codes again. I ordered a new air meter, and have my fingers crossed.

John C.

This is just a guess... and it may be TOTALLY off the mark, but something like this happened to me when I went to pick my VX up after having the SC installed (the first time), no check engine light or anything.

They told me the VX was ready, and we took it for a test drive. I noticed right away that it wasn't getting much more power (nothing like I thought it should). As we took an off ramp and were coming to a light, the engine began idling strangely, reving then backing down. Even with the brake pedal depressed it was hard to keep from bumping the car in front of me. We went back to the shop.

After about an hour of fiddling, they told me it was ready. They said they had forgotten to put a plug on a hole on the SC. I guess some sort of vaccum plug. We went for the test ride, and I haven't had a problem since.

Today I was changing my oil and looked at the SC a bit. I felt around, behind the throttle and cruise control cable, and I felt a small nipple :) tube with a cap on it. I'm not sure if this is the one that had the missing cap, but it would be an easy fix if this was your problem!

I've pretty much eliminated the idea thats its a vac leak. I took my propane torch, and carefully sprayed the entire intake with gas. Normally if there is any vac leak you would detect a change in idle from this.

I opened the MAS, its a 3 hotwire setup. one of the filiments is slightly discolored, maybe some imputiry burned into it? I tried cleaning it with brake cleaner, but no changes.

My next thoought if this new MAS doesn't solve the problem is fuel pressure. I'm sure i can solve this by upping the pressure, but I didn't want to have to mess with that.

John C.

Let me know if you have come up with the solution to this problem. My VX has been triggering the same codes since I put the supercharger on, just not as frequently as you are. I replaced the MAS when I got a low reading on the MAS. Seemed to be OK for a while and the other day it set off another code. I have noticed a strong catalytic converter smell when I drive at highway speeds, about 65 - 80 MPH. This is also when the code seems to go off. The car will hesitate under accelleration and idle roughly. I am pulling my hair out trying to figure this one out. I have checked all vacuum lines and ther appears to no vacuum leak. I would appreciate any help or suggestions you come up with.

How do you guys get the code #'s without a code analyzer? I have a check engine light and would like to get some direction on where it might be coming from.

Randy

I have a buddy at the local Isuzu dealer, that helped me install the supercharger. He's a great guy and an Isuzu certified master elite mechanic. I just take it to him and he hooks up the analyzer (at no charge to me) when I get a check engine light. We can then read the codes. Maybe you should try making a friend at your dealer.

Quote:

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Originally posted by Randy
How do you guys get the code #'s without a code analyzer? I have a check engine light and would like to get some direction on where it might be coming from.

Randy

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Go to an Autozone.

We have AutoZone's here, but they are just parts stores. There is no built-in auto shop. Do they have a designated code breaker that rushes outside with the majic wand?

I get the codes with a metal colander and tin foil.....

http://www.actron.com/cp9135.jpg

Thats what I use. I think I paid about $130 new. It will work on anything 1996 or newer.


John C.

Quote:

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Originally posted by Randy
We have AutoZone's here, but they are just parts stores. There is no built-in auto shop. Do they have a designated code breaker that rushes outside with the majic wand?

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Actually, yes, they probably do.

Even the Autozone parts-only stores around me have their nifty little carts for battery/electrical diagnostics. It's a good bet they all have code scanners too.

-Daver

I had been experiencing a rough idle, as well as an extremely high idle once stopped. When i would come to a complete stop my engine would be going between 1500, and 2500 RPMS. I had also been experiencing the lack of power, it was like it wasnt getting any gas and would start to stall. I finally replaced my Idle Air Control Valve and have had great success. The steps that led up to this simple fix were, Intake Gaskets, Timing Belt, Valve Adjustment, and cleaning the throttle body. So far everything is back to normal.

New air meter....no change. I'm taking one of the fuel rail banjo bolts in to work, and tapping it 1/8" ips to install fuel pressure gauge.

Anyone know what idle pressure should read?

John C.

your fuel psi at idle should run 30psi to 35psi , how many miles is on your truck and how long has the sc been on . as the boost psi runs up it bring up the fuel psi to add more fuel ( higher then stock witch puts more load on the pump ) if your pump is week it will run fine as long as you are not under boost and will lean out as the psi goes up ! this can burn a piston ! you need to get it checked !!!!! you may wont to ask Tone if he can find out from Alpine Developments what the fuel psi should be under boost ( 45psi at 1psi of boost ,50psi at 2psi of boost ??? ) so you can check it yourself
hope this helps :wave: