1999 Chev Venture - PO131 & PO137

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Tim Martin
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1999 Chev Venture - PO131 & PO137

Post by Tim Martin »

This 99 Venture recently had an engine change. New GM unit in another shop, and judging by the looks of some things, not someone that takes pride in the finished products appearance. The issue ever since is a severe power loss at part throttle. The engine starts up fine, idles fine - has 19" vacuum at idle. Only PCM codes are PO131 and PO137. Both are lean running codes for the oxygen sensor and the catylist monitor. I admit I did not check fuel pressure due to the difficulty of reaching the service port which is behind the power steering pump. However, while watching data stream on my scan tool and lab scope, koeo tps voltage is .57v, koer voltage for map is 1.10, maf is 5 grams at idle, os sensor is fluctuating fine, ect is 197, air intake is 88. At 3,000 rpm the tps is 1.25v, map is 1.15, maf is 25 grams, o2 is still doing fine between .19 and .97, vacuum is still at 19" vacuum. At 3800 rpm is where the pcm goes into open loop, o2 sensor and cat monitor flat lines at .10, maf is 36 gms, vacuum goes to 0, air-fuel ratio is 15.7-1. Some where there is an issue but I have not discovered it yet. It is difficult to drive down the road cause you can't take off as you'd like to. It has no power. However, if you real slowly take off, you can eventually coax it to 70 mph until you need power and then your'e done. So long as the throttle is not pushed very hard, no codes and no issues.

I am about to do what I had hoped I wouldn't need to do - remove the power steering pump to check fuel pressure. It does have a new fuel filter though and if I unhook the vacuum line at the fuel pressure regulator the engine speed raises about 50 rpm or so.

We got us an issue.
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Re: 99 Chevy Venture PO131 & PO137

Post by ricmorin »

Fuel pressure check is a must. Also, try disconnecting the MAF and see if it runs better.
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Re: 99 Chevy Venture PO131 & PO137

Post by Tim Martin »

ricmorin wrote:Fuel pressure check is a must.
Awwwww. I figured someone was gonna be saying that.

Will post that as soon as I can get it checked.
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Re: 99 Chevy Venture PO131 & PO137

Post by Tim Martin »

I just disconnected the MAF and it made absolutely no difference in the problem except to set a code.

Now i really got me an issue as I got to do what I was not wanting to do - take the power steering pump off.
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Re: 99 Chevy Venture PO131 & PO137

Post by Jeff @ Able Auto »

I have adapters to go inline at the fuel filter...might wanna check that.
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Re: 99 Chevy Venture PO131 & PO137

Post by ricmorin »

The test port is behind the PS pump? My guy remembers that from the dealer days. He thought you could still get an adapter on there without R&R, but it's tough.
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Re: 99 Chevy Venture PO131 & PO137

Post by Tim Martin »

Jeff @ Able Auto wrote:I have adapters to go inline at the fuel filter...might wanna check that.
Adapters?

Got a tool number for it/them?
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Re: 1999 Chev Venture - PO131 & PO137

Post by steven kiser »

Pulling the vac line off will normally raise the rpm's. Try driving it with the line off and see what happens. Normally as you accelerate the vac pressure drops allowing more fuel pressure at the injectors. The first and i mean the first thing i look for are non connected ground wires or a bad connector at the temp sensor for the pcm.


NOW HERE WE GO AGAIN WITH STEVES CONSTANT REMINDER ABOUT CLEANING UP OTHERS ISSUES.

Anytime i get one of these beauties in the shop i insist on not only repairing the issue that is present but since i'm going to be the owner of this pos from now on all other issues. I've spent afternoons searching salvage yards for missing mounts, brackets, etc. This may be an issue of an over zealous tech ( :shock: hate using this description since the vision of two kids trying to pound a square peg into a round hole flashes in my mind then goes to them grown up installing a "universal" battery telling the customer that they're experts in making things fit) folding back the fuel line and bending it. May have pressure but no volume. May possibly be a 02 issue. These issues can take it's toll on a good tech since you're up against not only the initial issue but usually a lot of so called repairs or creative resolutions by a creative expert. Sometimes the initial fault is easily found and resolved but the creativity takes days of emotional frustration and energy. Remember, by working on this you're removing any responsibility from the installer and shouldering any and all future issues. Happened to me years and years ago. A person came into my shop with a skip after he paid another shop for a major tune up and had lost his car for a week because of a skip. He brought it in and #'s 5&7 were crossed. Repaired it and off he went. He came back every week with issues stemming from the initial tune up. He paid me to straighten out the firing order and the initial work cost him big money and it was all my fault since i was the last to work on it. From that day on i insist on removing all parts that were installed and putting mine in. If i'm going to be responsible it's going to be under my rules and regulations. Good luck and take care to protect yourself and your reputation.
never argue with a fool, they'll drag you down to their level and beat you with experience
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Re: 1999 Chev Venture - PO131 & PO137

Post by Jeff @ Able Auto »

Tim I have a OTC fuel system test kit that has a LARGE selection of test adapters. Plus I have several adapters that were made for Chrysler products that went in line, primarily for the LH cars. They have the quik connect adapters on each end with a test port in the middle. Really dont remember what parts I used but I cant remember the last time I couldnt test a car. Did have to buy some special adapters a while back for Kias I believe. Removed the fuel line at the rail and installed the adap. with longer bolts the have a test port. Sorry I cant give ya the exact part numbers.
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