Need help please, new motor, now pings bad

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Tuffy
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Re: Need help please, new motor, now pings bad

Post by Tuffy »

Update:
Replaced the fuel injectors with brand new Bosch 26 lb. at 49 PSI injectors. The pinging is still there and may even be worse! I rechecked with the O2 sensor, same readings, around 15:1 AFR. The 02 sensor was used on another vehicle and it read differently, so we know it is working correctly. I am now leaning towards finding another computer. Maybe the computer I got from the junk yard when I first injected this thing is no good?

I just do not know where to go from here, it has been a year since the last motor blew, I have been fighting this all summer. I really want to drive this but just do not want to cause damage to my new motor by the pinging. It is quite noticeable. What would cause this thing to run so lean? The motor was timed by the engine builder while assembled, we are 100 percent positive it is timed correctly.

Ideas?
Tuffy
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Re: Need help please, new motor, now pings bad

Post by Tuffy »

Anyone??

Can someone explain why my AFR remains the same with the new injectors? Is the computer not letting the injectors flow enough fuel? Should I try a new computer for the MPFI? Like I said, I really do not know what to try next?
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SilverXJ
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Re: Need help please, new motor, now pings bad

Post by SilverXJ »

What did the O2 sensor read on the other vehicle?

What about the stock O2 sensors? When were they last replaced?
Tuffy
Where's the "any" key?
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Re: Need help please, new motor, now pings bad

Post by Tuffy »

02 sensor read 12 on different motor as it was a race car. My stock 02 sensor was replaced prior to starting the new engine for the first time. When the motor was started for the first time to break in the cam the exhaust became cherry red all the way to the catalytic converter and into the muffler. After the cam break-in the red color seemed to go away the more we ran the motor. Could this possibly have ruined the new stock 02 sensor?

When I drive the jeep and hear the pinging, it sounds like it is almost going through the entire exhaust. It is very noticeable and makes one want to pull out of the throttle. The pinging seemed to get worse with the new injectors.

The catalytic converter was new about 3-4 years ago when I first injected the jeep on the old motor.

I have read about using a "toothpick method" to set the distributor, what is this process? Maybe it is not set correctly? Plugs, wires, cap, rotor, coil are all new. Only thing left is sensors (IAC, TPS, Etc.) and the computer! The computer was from the junk yard out of a 1991-92 jeep cherokee I believe, the rest of the system is from a 1995 Grand Cherokee. This should not matter will it?

The motor idles wonderfully, and is real smooth. Just pings bad mid-upper throttle. Motor exhaust seems extra hot as well, engine temp seems normal, but get a great deal of underhood high temps. Another thing I noticed is that it does not seem to ping when it the motor is just started and not up to operating temp yet. Though the wide band 02 sensor shows no change in the AFR at start up vs. full operating temp.

The engine builder is very confident the motor is timed to the cam correctly as it was done with a cam dial?
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SilverXJ
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Re: Need help please, new motor, now pings bad

Post by SilverXJ »

Where did the distributor come from? I know some years need the tooth pick and some don't. Also, what CPS and transmission are you using? I don't know if CPS's are clocked exactly the same on all transmissions.

Exactly what brand/model wideband are you using? The AFR will fluctuate and is almost never 12.0:1 or 15.0:1. A good wideband will have at least one decimal place.

Exhaust glow is normal on break in, but not all the way to the cat or when usually driving.
Tuffy
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Re: Need help please, new motor, now pings bad

Post by Tuffy »

The distributor was obtained out of the junk yard. What is the tooth pick method, what does it do or what is it? I do not understand what that is? Could this be the problem?

The CPS is a Hesco model that runs off the front of the crank shaft and uses a special harmonic balancer/pulley to obtain signal.

The wide band 02 sensor is an analog guage, not digital. It is a FAST (Fuel Air Spark Technologies) Model # 170634

The exhaust only glowed like that during the cam break in, it never did it again.
Tuffy
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Re: Need help please, new motor, now pings bad

Post by Tuffy »

Could it be possible that my distributor is out of adjustment or alignment? How would one test this, perhaps it is not timed correctly to the motor? Like I said, the engine builder is very confident that the motor is timed correctly. But, what if the distributor is not timed to the motor, or aligned correctly?

I am really grasping for anything at this point. I cannot believe I can't figure this out. It is so frustrating when you have a brand new motor in a jeep that you cannot drive due to an issue like this.
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SilverXJ
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Re: Need help please, new motor, now pings bad

Post by SilverXJ »

Tuffy wrote:The distributor was obtained out of the junk yard. What is the tooth pick method, what does it do or what is it? I do not understand what that is? Could this be the problem?
What year did it come off of? Does it come off a Cherokee or the Grand (don't know if they are different or not)? A toothpick is inserted in to the distributor housing and passes into the cam sensor reluctor wheel. That locks it into position then you drop the distributor in. I don't remember what years that applies to.
The CPS is a Hesco model that runs off the front of the crank shaft and uses a special harmonic balancer/pulley to obtain signal.
I've read that this can be very tricky to index properly. Its such a small diameter compared to the original off the flexplate that very small movements result in great timing changes. I would re check that.
The wide band 02 sensor is an analog guage, not digital. It is a FAST (Fuel Air Spark Technologies) Model # 170634
That sounds like its fun to read. How does it calibrate?
Tuffy
Where's the "any" key?
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Joined: August 1st, 2012, 7:48 am
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Re: Need help please, new motor, now pings bad

Post by Tuffy »

The distributor and all MPFI, Head, manifolds, and wiring harness are all from a 1995 Grand Cherokee.

The wide band is actually really easy to read as the scale goes from 0-20, quite easy to read that's for sure. Not sure how it calibrates, nothing in the directions, but once you start the motor, the needle goes through a check/warm up per the directions, and that is what it has been doing. I assume it is working correctly.

The CPS is mounted with a Hesco mount, there is no adjustment other than how far away from the balancer the sensor is. The correct spacing is the thickness of a match book, real simple. The mount is not adjustable and mounts using the oil pan mounting bolts.
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SilverXJ
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Re: Need help please, new motor, now pings bad

Post by SilverXJ »

Does the reading fluctuate at all when driving?
Tuffy
Where's the "any" key?
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Re: Need help please, new motor, now pings bad

Post by Tuffy »

Gauge needle fluctuates only slightly. Still doesn't fix the pinging though. The new injectors flowing more fuel made the pinging seem more pronounced.
Tuffy
Where's the "any" key?
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Posts: 21
Joined: August 1st, 2012, 7:48 am
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Re: Need help please, new motor, now pings bad

Post by Tuffy »

Could someone please post the instructions or method to install the distributor into the motor and the correct positioning while at TDC? I would like to check this to make sure I have the distributor correct. I understand the distributor is the cam sensor, is there a chance my cam sensor is bad, if so how would one know and what would the symptoms be?

I am trying everything here, what other sensors would cause problems? I have the crank position sensor set per the Hesco instructions, there really is no adjustment, just adjustment for the correct spacing so the sensor picks up the signal.

Thanks,
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