My first (and last I hope !) backfire

[plissken97]

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

[tccrab]

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

[plissken97]

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

[A26B]

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.

[plissken97]

Thanks Jerry for your feedback, this is really appreciated.
I will try your tips.

Originally Posted by A26B

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.

In these both cases, whatever the problem is, it seems that it is are located under the plenum !