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Gary
Gary, ASE Certified Technician
Category: Chevy
Satisfied Customers: 770
Experience:  Senior Technician
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3.1 won't accelerate. Like its smothered. New cat not the

Customer Question

3.1 won't accelerate. Like its smothered. New cat not the problem. No fuel in pressure reg vac line. Fuel filter good. Air filter good.
Submitted: 1 year ago.
Category: Chevy
Expert:  Super Mechanic replied 1 year ago.

Hello and welcome. My name is ***** ***** you for visiting the site, I will be happy to assist you today.

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******* THIS IS NOT AN ANSWER, I JUST NEED MORE INFORMATION ********

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What is the fuel pressure at?

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Are there any trouble codes stored?

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How many miles are on the engine?

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Customer: replied 1 year ago.

100343 miles. Where do I check fuel pressure ? How do you pull codes from this obd1.

Expert:  Super Mechanic replied 1 year ago.

I am sorry, assuming a Lumina car, not the van?

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Also, the codes may be able to be read with the flashing of the check engine light. Does it have a 12 pin DLC connector or a 16 pin. Here are the pictures that show the 2, thanks

Expert:  Super Mechanic replied 1 year ago.

I can get the instructions for the fuel pressure test and put them in a PDF file, (it is rather large) and send it to your email address for a little bit more.

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You will just have to accept the additional service offer and ENTER your email address in the private section so that I can see it. I do not have access to your email address, Thanks

Customer: replied 1 year ago.

Lumina car. 12 pin. Where do I jump retrieve codes

Expert:  Super Mechanic replied 1 year ago.

Let me start by saying that any money that you paid, or if you have a subscription, that money stays in your account until the answers are rated, (positive) regardless of how fast or how long it may take to get finished. You can FOLLOW UP AT ANYTIME, even after rating.

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Here is a link to the instructions for reading the codes, thanks.

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https://www.dropbox.com/s/lr9hw07igql3qfc/Data%20Link%20Connectors.pdf?dl=0

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Please don’t forget to rate the answer in a positive way, . EVEN IF YOU HAVE A SUBSCRIPTION ****THAT IS THE ONLY WAY I GET PAID ****

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Customer: replied 1 year ago.

Will check codes. 37 lbs fuel pressure at rail port.

Expert:  Super Mechanic replied 1 year ago.

That is a little low, you may want to see how the pressure holds up under a load. should be 40-47 psi. See if any codes show up, I have had some with bad MAF sensors and they really had a bad lack of power, (other than the usual sputter), thanks

Customer: replied 1 year ago.

This vehicle does not appear to have a maf ?I ordered one its here but I look at tbody no maf ?

Expert:  Super Mechanic replied 1 year ago.

Normally we get paid for the original answer(s) before any follow ups, but most all of the 95 Lumina cars with the 3.1 ( 8th digit of the VIN, "D") was produced with a MAF sensor in the air intake but I do remember some, (experimental models) with MAP sensor and they left the MAF's out. I guess it doesn't have one in the air duct? (see picture), thanks

Customer: replied 1 year ago.

Still have not solved original question. No maf sensor. 40 lbs fuel press. At load . my 12 pin diag conn. Only has 2 wires in it at the A and M positions. If you jump those two it does nothing. ? Still no power and poor acceleration. ??

Expert:  Super Mechanic replied 1 year ago.

Normally the timing chains on them don't go bad at 100K but you may want to see how the compression is to be sure. If the cat is not the problem and the fuel pressure is good, that doesn't leave many other things beside the compression or late valve timing.

Customer: replied 1 year ago.

Map ? Egr ? Any word on how to retrieve codes on this car with the wires at A and M in connector ?

Expert:  Super Mechanic replied 1 year ago.

If there is no wire to the "B" terminal then a Tech1 scan tool is needed to read the codes. If it really won't accelerate and really lacks power it is not likely to be a sensor, (other than a MAF, which it doesn't have). the EGR won't do that and the MAP sensor doesn't have the capabilities to dominate air/fuel rates as you accelerate.

Customer: replied 1 year ago.

I am baffled it runs perfect and I means perfect. No missing stumbling just has no power. I would have bet it was convertor. Lost you think anyone else might have an idea ?

Expert:  Super Mechanic replied 1 year ago.

Possibly but they might want to start with the engine's compression, after all that has been checked so far. Which is what I said. Then, say they tell you the problem, (timing chain, etc.) and get paid for the time that I have spent on it. Or what seems to happen quite often is that no other experts take it on and the customer gets aggravated and gives me a negative rating. We can give it a try. Thanks and please come again, anytime.

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Expert:  Super Mechanic replied 1 year ago.

Possibly but they might want to start with the engine's compression, after all that has been checked so far. Which is what I said. Then, say they tell you the problem, (timing chain, etc.) and get paid for the time that I have spent on it. Or what seems to happen quite often is that no other experts take it on and the customer gets aggravated and gives me a negative rating. We can give it a try. Thanks and please come again, anytime.

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Customer: replied 1 year ago.

Great thanks

Expert:  Gary replied 1 year ago.

Hi there,

Just some more questions to help me help you.

Your engine seems to run fine with no stumble on acceleration, but lacks power?

You have changed the cat convertor, how about any other mufflers in the exhaust system?

Can you drop the exhaust after the cat and see how it performs?

Gary

Customer: replied 1 year ago.

I blew shop air thru exhaust whenbi had cat off. But you might be right let me cut it drive it and reweld it if no problems.

Customer: replied 1 year ago.

Just some fuel pressure info I accumulated while waiting. Pressure koeo at rail 39lbs. 39 koer . 45 koer and vac dissconected from pressure reg.

Expert:  Gary replied 1 year ago.

Your fuel pressure sounds ok to me.

Shop pressure is not enough volume of air to test muffler flow.

I'm happy to wait for you, have seen it many times with collapsed mid or rear mufflers.

Gary