09-23-2024 | #1 |
Join Date: Jan 2020
Location: France
Posts: 8
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My first (and last I hope !) backfire
Hi guys,
I'm Julien, I live in France and I owned for 4 years now a beautiful black 1990 ZR-1. I made this backfire last friday... My SES light came on. I got 3 fault codes after my diagnosis : H33 H45 H65. I solved 2 codes which were the H33 and H65 by putting in place the MAP sensor hose at the back of the plenum. Unfortunately, it remains my SES light with a H45 code. It says "Oxygen Sensor (System Rich)". Can you help me to solve this issue ? Thanks a lot. Julien |
09-23-2024 | #2 |
Join Date: Oct 2004
Location: Folsom CA
Posts: 1,653
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Re: My first (and last I hope !) backfire
Julien:
The backfire might have popped off the pvc hoses when it popped off the hose on the Map sensor. Also check the fuel regulator vacuum hose, it lives on the bottom of the fuel pressure regulator. And your Map sensor might be still leaking a little, especially if the hose has gotten soft over the years. If the Map sensor isn't working right, it will cause the motor to run rich will cause the codes you're still seeing. https://www.jerrysgaskets.com/hose-m...ew-90-95-13d4/ Crabs
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TomC '90ZR1 #792 Honorary Pirate [B]If it ain't FUN, you're doing something terribly WRONG. [/B] Last edited by tccrab; 09-23-2024 at 09:23 PM. |
09-24-2024 | #3 |
Join Date: Jan 2020
Location: France
Posts: 8
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Re: My first (and last I hope !) backfire
Hi Crabs, and all the members,
Thanks for your reply. I double-checked all these hoses, and they are okay. I noticed that when I turn the ignition on without starting the V8, the vacuum pump on the passenger side, near the front right wheel, keeps running : it starts/stops 3 secondes then restarts/restops etc. However, I decided to start the engine, and it runs very well. There's no SES light, and the car seems to be in great condition (the car idle is ok : 700/750 rpms), although I haven't driven it on the road yet due to the bad weather in Paris in order to be sure that all the horsepower are delivered. I ran another diagnostic test and there are no more codes. I am a bit worried about the vacuum pump running continuously. If anyone has any input, I'd appreciate it. Thanks a lot et thank you all. Julien Last edited by plissken97; 09-24-2024 at 08:55 AM. |
09-24-2024 | #4 |
Join Date: Dec 2003
Location: Arcadia,OK
Posts: 3,393
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Re: My first (and last I hope !) backfire
Sounds like you have a vacuum leak, likely in the Secondary Port Throttle (SPT) System. There is a rubber hose connection, near the alternator, in the hard plastic line from the vacuum pump to the SPT system. Disconnect the line there.
Key on- Engine off, put finger on end of hose going to the vacuum pump to isolate the pump from the SPT system. The pump should only run a short time and stop until you release your finger. If this is the case, the vacuum leak is in the SPT system. Re-connect the hard plastic line. Before removing the plenum, Remove the vacuum line from the pipe located on the driver side of the plenum at the center. Key on, Engine off, plug the removed hose. If the vacuum pump stops and/or the stop cycle is significantly longer between starts, the problem is likely the check valve under the plenum is faulty. If not, then the leak is under the plenum.
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Jerry Downey JERRYS LT5 GASKETS & PARTS http://www.jerrysgaskets.com 1994 ZR-1, Black/Black, Lingenfelter Aerobody, 416cu in, 3.91 gears, coil-over susp, Brembo brakes, etc. 2016 Black-Red, 3LT-Z51 Auto 8-speed. |
09-24-2024 | #5 | |
Join Date: Jan 2020
Location: France
Posts: 8
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Re: My first (and last I hope !) backfire
Thanks Jerry for your feedback, this is really appreciated.
I will try your tips. Quote:
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09-24-2024 | #6 |
Join Date: Dec 2003
Location: Arcadia,OK
Posts: 3,393
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Re: My first (and last I hope !) backfire
True, but as a temporary measure, if the check valve is bad, you can install a good check valve on the outside of the plenum, between the pipe & hose, until you get around to pulling the plenum
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Jerry Downey JERRYS LT5 GASKETS & PARTS http://www.jerrysgaskets.com 1994 ZR-1, Black/Black, Lingenfelter Aerobody, 416cu in, 3.91 gears, coil-over susp, Brembo brakes, etc. 2016 Black-Red, 3LT-Z51 Auto 8-speed. |
09-24-2024 | #7 |
Join Date: Jan 2020
Location: France
Posts: 8
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Re: My first (and last I hope !) backfire
So I followed your tips and:
The issue comes from the Throttle System. It does not come from the check valve. In conclusion, the problem seems to come from under the plenum... However, after I unplugged/plugged the hose near the alternator (the one that goes to the vacuum pump), I noticed that the vacuum pump now starts and stops every 10 seconds approximately, not as fast as before. Do you think I still have a leak? Thanks a lot. Julien Last edited by plissken97; 09-24-2024 at 05:23 PM. |
4 Weeks Ago | #8 | |
Join Date: Dec 2003
Location: Arcadia,OK
Posts: 3,393
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Re: My first (and last I hope !) backfire
Quote:
It's not something that urgently needs resolved.
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Jerry Downey JERRYS LT5 GASKETS & PARTS http://www.jerrysgaskets.com 1994 ZR-1, Black/Black, Lingenfelter Aerobody, 416cu in, 3.91 gears, coil-over susp, Brembo brakes, etc. 2016 Black-Red, 3LT-Z51 Auto 8-speed. |
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4 Weeks Ago | #9 |
Join Date: Jan 2020
Location: France
Posts: 8
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Re: My first (and last I hope !) backfire
Thanks Jerry.
As soon as I can, I'll drive and test my ZR-1 at full power to see if everything is ok, if I have all the power available. I will see if the SES light is displayed. Thanks for helping. Julien |
4 Weeks Ago | #10 |
Join Date: Oct 2023
Location: Germany
Posts: 11
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Re: My first (and last I hope !) backfire
Salut Julien,
I'm also french I also did what Jerry recommended when you get a failure from the check valve of the secondaries vaccum system under the plenum. I placed it outside of the plenum on driver side as I didn't have the capability to lift it up at that time. Worked like a charm. The vacuum is held for 2 to 3 minutes for me, it was only 3 seconds initially. I agree with Jerry that it is not a "critical" thing to solve. However, your pump will cycle quite a lot, meaning that you are "logically" shortening the life of the pump. I also recommend you to purchase one of these vacuum pumps to really measure if your system is holding vacuum properly (I have a Mityvac MV8000 I think). There might be other vacuum components inside which are faulty (solenoid, vacuum tank....). If you do not have such pump, then the cycling time of the pump can only give such info. But I don't see how the secondaries vacuum system correlate with your rich oxygen DTC code. I would have a look at the fuel pressure regulator vacuum connection (if clogged) as proposed by tccrab and mesure the fuel pressure at the fuel rails. Bonne chance! Guillaume |
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