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Power loss Issues, possible limp mode

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Old Feb 20, 2017 | 07:37 PM
  #21  
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Originally Posted by gsasca
Already bought all the parts I need. Found a red one at a salvage yard in Dallas and got everything I needed for pretty cheap. Thankfully that means all OEM parts, so all I'm worried about now is getting it running right!
Also, it was right at 58 psi last time I had it on.
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Old Feb 23, 2017 | 12:01 AM
  #22  
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I would check the compression at this point.

If you can do both a leak down test and a regular test it will give more information obviously. If you do a leak down test and have a cylinder that is leaking fast, try to hear where the leak is with a mechanics stethoscope or ear on a long screw driver. Listen to see if it is hissing through the intake or exhaust manifolds (this would suggest a valve related issue).

If the leak down test checks good but the dynamic compression isn't then you may have a clogged exhaust.

Any comp test will provide some information.
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Old Feb 24, 2017 | 07:28 PM
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Good luck with everything you got quite a project on your hands. Usually people cross the 02 sensors when installing headers which causes issues
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Old Feb 27, 2017 | 06:43 PM
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Originally Posted by Rob 02
I would check the compression at this point.

If you can do both a leak down test and a regular test it will give more information obviously. If you do a leak down test and have a cylinder that is leaking fast, try to hear where the leak is with a mechanics stethoscope or ear on a long screw driver. Listen to see if it is hissing through the intake or exhaust manifolds (this would suggest a valve related issue).

If the leak down test checks good but the dynamic compression isn't then you may have a clogged exhaust.

Any comp test will provide some information.
Looks like this is the route I need to go. The O2's are plugged in with no effect. Engine still would rev right or give me any power. I still do not have a check engine light.

Would a clogged exhaust not give out a check engine light?
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Old Mar 1, 2017 | 01:46 AM
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Is it easiest for you to lift the car up and remove the mid pipes or remove a few spark plugs and do a compression check? What tools do you have at your disposal?

By the looks of your car, I am assuming that a big truck backed up on the hood in a parking lot. For liability reasons, the insurance company declared it a total loss. The previous owner took off his expensive exhaust and quickly threw threw the old one back on.

If he stuck the exhaust back on in haste then I would want to raise the car and check the hole thing out.

If there was a performance exhaust on the car then it is likely that there were a few more performance modifications to your car that may be beneficial.
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Old Mar 4, 2017 | 02:07 PM
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Originally Posted by Rob 02
Is it easiest for you to lift the car up and remove the mid pipes or remove a few spark plugs and do a compression check? What tools do you have at your disposal?

By the looks of your car, I am assuming that a big truck backed up on the hood in a parking lot. For liability reasons, the insurance company declared it a total loss. The previous owner took off his expensive exhaust and quickly threw threw the old one back on.

If he stuck the exhaust back on in haste then I would want to raise the car and check the hole thing out.

If there was a performance exhaust on the car then it is likely that there were a few more performance modifications to your car that may be beneficial.


That's my current setup. It shouldn't be too hard to take the exhaust pipes down, but I'm not sure how to check the cats. It's all welded so I couldn't get a good look. All I could do is put a leaf blower to it.

I just finished cleaning the MAF sensor and throttle body. Throttle body wasn't bad but the MAF was very dirty. I saw slight improvement. I can feel some of the power back but the idle is still rough, still doesn't have a lot of power, and the rpms still take a second to come back down. Still no check engine light.

I am am going to try the exhaust next. Going to try to get it today but need to wait for the pipes to cool down. I'll save the compression and leak test for last. Could the TPS also be causing the issue?
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Old Mar 4, 2017 | 03:00 PM
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Originally Posted by Rob 02
Is it easiest for you to lift the car up and remove the mid pipes or remove a few spark plugs and do a compression check? What tools do you have at your disposal?

By the looks of your car, I am assuming that a big truck backed up on the hood in a parking lot. For liability reasons, the insurance company declared it a total loss. The previous owner took off his expensive exhaust and quickly threw threw the old one back on.

If he stuck the exhaust back on in haste then I would want to raise the car and check the hole thing out.

If there was a performance exhaust on the car then it is likely that there were a few more performance modifications to your car that may be beneficial.
As far as performance mods, I only see a Blackwing air filter. Don't see anything else being done. If they had performance exhaust and headers, they would have needed to tune it correct? Could a tune possibly be causing these issues?
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Old Mar 4, 2017 | 05:13 PM
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Originally Posted by gsasca
As far as performance mods, I only see a Blackwing air filter. Don't see anything else being done. If they had performance exhaust and headers, they would have needed to tune it correct? Could a tune possibly be causing these issues?
Another update, I took the exhaust off. Put a leaf blower to it and didn't feel any resistance. I turned on the car with no exhaust and it was doing the same thing. Absolutely no change in the idle. I don't think the exhaust is the cause either. I guess compression and leak test it is.

Here is a pic of the rear O2 btw


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Old Mar 5, 2017 | 05:18 PM
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Don't forget to check for intake leaks as well. Vacuum lines, PCV, AIR system... might want to make sure everything between the MAF and the throttle body is OK as well. Speaking of the MAF, you might want to get that checked too. It sure looks like it may have taken a pretty good whack in the wreck, based on the condition of the hood.

Just a guess here, but if the throttle position sensor isn't working, could that cause issues?
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Old Mar 11, 2017 | 04:23 PM
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How do you check the fuel pressure? I said earlier it was at 58 but that was oil pressure. I don't see a pressure gauge at the fuel rail.

I check all vacuum lines by spraying carb cleaner with no effect. I am about to do a compression test. What should the psi be at each cylinder?
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Old Mar 11, 2017 | 11:47 PM
  #31  
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You can get a fuel pressure gauge from Harbor Freight or from a friend.
At the end of the fuel rail there is a Schroeder valve.

The pressure should read around 58psi at idle and raise with throttle.
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Old Mar 13, 2017 | 09:54 AM
  #32  
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Originally Posted by Rob 02
The pressure should read around 58psi at idle and raise with throttle.
The fuel pressure is constant, spec is between 55-60psi.
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Old Mar 25, 2017 | 09:55 PM
  #33  
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I borrowed a friends scanner today just to get a better idea of what was going on. Of course there was no code, but I'll post some of the data I got while the car was idle.




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Old Mar 27, 2017 | 07:40 PM
  #34  
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Also, I did both the fuel pressure check and compression test.

Fuel pressure was 57 when key was in on position, and 58 when the car was running. I also let it sit in on for about 10 mins to see if I lost fuel pressure, and it actually went up by 2 psi.

Compression test was good too. 178-180 on all 8 cylinders. Almost no deviation in PSI.

The spark plugs were black when I pulled them out however. These were brand new spark plugs. I've turned on the car maybe 10 times since putting them in.



Side note: I also found an unplugged wire that I have no idea where it goes.
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Old Mar 27, 2017 | 07:41 PM
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Picture of the wire


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Old Mar 27, 2017 | 09:30 PM
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Also, all the injectors ohm'd between 13.0 and 14.0.

Every single spark plug was dry fouled, so that means timing issue or vacuum issue right?
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Old Mar 27, 2017 | 11:07 PM
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That looks like too big a big plug gap. Try around 0.035".
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To Power loss Issues, possible limp mode

Old Mar 28, 2017 | 01:35 AM
  #38  
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It was at 0.04", and the same issue was happening with the old Spark Plugs. I don't think it's the gap honestly.
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Old Mar 28, 2017 | 02:10 AM
  #39  
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It was at 0.04", and the same issue was happening with the old Spark Plugs. I don't think it's the gap honestly.
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Old Mar 28, 2017 | 09:59 AM
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The fuel trims in your pics are out of whack. One side is high positive and the other side is high negative. Maybe your front O2 sensor wires are swapped side to side. Try swapping the plugs on the sensors.
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