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My check engine light has been on for months, in addition to my exhaust blowing black sut and rough engine idle. I had a system check performed at a local mechanic shop. Their diagnosis was I had 2 fuel injectors losing pressure causing my problems($1000 dollar repair estimate to replace injection system). Does this sound legitimate with the injectors losing pressure causing this? I know the repair estimate is about right. I appreciate your responses.

2007-08-06 15:35:13 · 7 answers · asked by Fit4life 1 in Cars & Transportation Maintenance & Repairs

7 answers

sounds like you mean the 2 injectors are leaking as in leaking into the cylinders hence the black sut and rough idle. Ive seen it a few times. also seen the fuel pressure regulator leaking do that too since its inside the intake. Get a second opinion but its a legit problem

2007-08-06 15:49:54 · answer #1 · answered by Bubb@ 2 · 0 0

Black sut blowing from your exhaust is an obvious indication of an engine that is running rich. Another obvious symptom of a rich air/fuel mixture is a rough idle. A rich air/fuel mixture is normally not caused from fuel injectors having 'low pressure'. What type of fuel injection is on the 96 Suburban? If it is anything other than throttlebody injected it will have more than 2 injectors. All of the injectors are being fed fuel thru the one and only fuel pressure regulator so all injectors will have the same fuel pressure. I would recommend replacing all of the rubber vacuum hoses and rubber vacuum fittings on your engine as they are over 10 years old and probably dry rotting and/or cracking causing vacuum leaks. There are several causes for the symptoms you have described. Here is a list (not to be construed as a complete list though) of the most obvious causes:
1. Your EGR (Exhaust Gas Recirculator) not operating properly (normally caused by insufficient vacuum or carbon fouling).
2. Malfunctioning Heated Exhaust Gas Oxygen sensors. These actually generate a small variable electrical voltage based upon the amount of unburned fuel present in the exhaust. When your oxygen sensors malfunction, or wear out, the voltage output decreases. The engines computer interprets this lower voltage as a lean condition so it will increase the injection time to try to enrichen the air/fuel mixture so the motor is not damaged.
3. Another possible culprit is a PCV (Positive Crankcase Ventilation) valve sticking in the closed position. During the power stroke, in each cylinder, there is always a small amount of exhaust gas that is forced past the piston rings. The more wear a cylinder has, the more exhaust gets past the rings. These gases actually pressurize the crankcase are and are normally routed thru the PCV valve and into the intake manifold 'after' the throttle body and mass air sensor. This is actually inert. It has no oxygen and basically just dilutes the oxygenated air and fuel mixture which decreases emissions and increases fuel mileage. When the PCV valve sticks closed there is no dilution of the incoming air/fuel mixture which allow it to be overly rich.

In Summary:
A PCV valve for a SBC (small block Chevy) costs less than $5.00 at most auto parts stores. It shouldn't take much more than another $5.00 to replace all of your rubber vacuum lines. I would replace these items first. If you don't notice your exhaust cleaning up with a few days then I would go ahead and replace your oxygen sensors. They can be pricy on some vehicles so I will not even suggest a price here but I can promise you they will be nowhere near $1,000 (the cost quoted to you to relplace your fuel injection system).

Finally, find a mechanic that you trust and have him run a diagnostic test of your vehicle. This will pull all trouble codes that have been read by the engine computer since the last time the codes were cleared from memory. He will be able to pinpoint the cause or causes of the sympotms and check engine light that you now have. Most mechanics are honest even though most will recommend replacing various components even though they aren't yet broke. Certain obviously worn parts should be replaced during the repair/replacement of another engine malfunction as the labor cost will far exceed the cost of the non-failed part. If the worn part isn't replaced while the mechanic had access to it and the part should fail within the following month the labor charge will be the same as for the previous repair. It only makes sense to replace another $30 part at the same time the labor charge of $600 rather than saving the initial $30 and paying an additional $600 the following month.

2007-08-06 16:44:48 · answer #2 · answered by cdw4105 1 · 0 0

This is a common failure on those type of vehicles. If Im not mistaken there was a recall perfomed by gm. If you talk to your local gm dealership they might do it at a very reduced price. I have a buddy with a 99 suburban that had 1 bad injector and gm replaced all 8 for free. he just had to be persistant.

2007-08-06 15:51:04 · answer #3 · answered by bdiym1 3 · 0 0

Check your work. It it worked before you messed with it, then you messed something up. It's as simple as that. 1-8-5-3-6-4-7-2

2016-05-20 02:28:21 · answer #4 · answered by ? 3 · 0 0

i don't think your Chevy would know if the injectors where losing pressure it would know if it was misfired it sounds like a 02 sensor

2007-08-06 15:55:37 · answer #5 · answered by Anonymous · 0 0

Get another opinion.

Change you air filter.
Your engine is getting too much gas, or not enough air.

2007-08-06 15:44:15 · answer #6 · answered by Mr. KnowItAll 7 · 0 0

probably map sensor or mass air flow sensor

2007-08-06 16:12:40 · answer #7 · answered by knuckels_mc 1 · 0 0

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