P0171/P0174 Help!

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- Pete C.
  
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posted
15 years ago

Thu, Jul 24, 2008 12:32 AM

I got a few fittings and extended my fuel pressure gauge. Got it cable tied to the windshield wiper arm, kinda scary (fire extinguisher on passenger seat). At any rate I took a ~20 mile RT spin, including 70mph highway and some 35mph city.

Fuel pressure seemed reasonable, ranging from a low of about 45psi under compression braking, to a high of around 65psi under hard accel. Most of the time holding cruising speed it was around 50psi or so.

It didn't log any codes during the trip (or the 120 miles yesterday), so nothing conclusive yet, but it does appear the problem isn't fuel pressure. I'm starting to suspect the injectors now. Unfortunately the injector connections are pretty bloody inaccessible for probing thanks to the upper IM in the way. I did check voltage at the ECM 1 fuse (feeds the injectors) and it is good. Grounds where I could check are good.

Given the fairly high cost of injectors and the need for 8 of them, I'd like to be able to test and confirm that they are really the problem before replacing them. It does seem to my feeble memory that they aren't clicking audibly like they used to. You can of course hear them click with a stethoscope probe on them, but not really by naked ear over the other noise.

Suggestions for testing the injectors?

Thanks.

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- Steve W.
  
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posted
15 years ago

Thu, Jul 24, 2008 7:40 PM

Well they are a PIA to do so I wouldn't bother just testing them. I would pull them and take them or send them to a shop and have them cleaned and flow tested. Not real easy to do that yourself but a nice flow bench makes it easy.

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Might have an idea.

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- Pete C.
  
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posted
15 years ago

Fri, Jul 25, 2008 3:24 AM

Somewhere I have the 3M fuel injector cleaner kit, I just can't seem to find it :(

If I have to actually pull them I may as well replace them since the time and effort to pull the upper IM to get to them combined with the lack of a second vehicle to take them anywhere makes it impractical.

I'm looking at options for in-place testing. Presumably I'll have to pull the connector off the VCM to access the connections, and put my bypass switch in place of the fuel pump relay.

It's really strange since it seems so intermittent. On 120 miles rt today it seemed to be running fine and no codes set. This evening for a short run to the grocery store it seemed to have issues and on popped the MIL. Really makes me suspect a connector problem, but I've checked nearly every one and the seem to be in good condition. I really need to get a logging scanner on it to try to catch where the problem is.