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Got MPI. Now can't loose PING

Well, now that I have MPI on my CJ7 I now have PING I can't get rid of. I'm running 91 octane (highest in California). JeepsRUs pulled the timing back

6 degrees. I put cooler spark plugs in at Hesco's recommendation. After all that I still have the ping.

From here I know of a couple of routes to go which actually can blend together.

First, an adjustable fuel pressure regulator which both Hesco and JeepsRUs said might be necessary. The downside is price. Hesco charges 180 something for this piece. Here I don't know if this will definitely clear up the ping.

The other route is the 4.0L head. I'm told that will definitely clear up any ping. Since I already have a 4.0L head sitting in my back yard all ready to go I was thinking of just going to that. I only need to get a 4.0L manifold to make it work. The downside of that is the amount of work I need to do. Basically tear the whole thing apart again to put the head and manifold on.

Anyone else run into this problem and found a work around?

Any other suggestions?

Oh, one other thing I noticed. After I put new plugs in I took a look at them to see their condition. It seems (and I've noticed this with the carb and two sets of plugs in the MPI) that a carbon trace forms down one side (about 10% of the radius of the white part) of the plug on all plugs. Is this normal or is this fouling and if it is fouling what could be causing it? Could it be the 4.2L head might cause this? Valves? What?

Thanks in advance,

Bill

Reply to
William Oliveri
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It sure sounds like it's running way too lean. Is there anything miswired or anything else that could cause it to run too lean?

Jerry

Reply to
Jerry Bransford

Why do you think it's running lean? What gives you that indication?

If anything I thought it would be running rich, that I have some hole in my exhaust manifold and the O2 sensor not compensating. Couldn't find one but just a thought trying to figure this out.

Thanks,

bill

Reply to
William Oliveri

An engine will just ping a lot easier if it's running too lean... and it can also be bad for the engine because it runs hotter inside the combustion chambers when it's running too lean. I'm really not much of an engine mechanic but a too-lean condition can sure cause symptoms that sound like yours.

Jerry

Reply to
Jerry Bransford

What I've heard regarding Mopar MPI kits and 258 engine is that year 83 and

84 have a greater propensity to ping that other years due to the crappy design of the head.

Mine is an 83 CJ7.

Also, It seems Ping is a common problem with MPI kits and 258 engines.

Since the Computer is controlling the Air/Fuel ratio I would think it shouldn't have a problem with either rich or lean. At least not to any extreme. JeepsRUs checked out the computer and didn't find it throwing back any error codes. Everything looks good except for the ping.

bill

Reply to
William Oliveri

Reply to
L.W.(ßill)

Hi Bill, Yes, the kit came with the Harmonic Balancer and the pickup sensor. If it wasn't hooked up correctly I would expect the computer revealing a problem which it hasn't so far.

What do you mean pull the spark plug back? Do you mean continue pulling the timing back? Sorry, still new on these terms.

Thanks,

Bill

Reply to
William Oliveri

Reply to
L.W.(ßill)

Bill, could the pickup distance make a difference? I basically eyeballed the distance from the balancer when I hooked it up. It looks as though it would be between the required/recommended .020 to .060 distance. If anything it could be too far away.

Also, any comments on the spark plug description in my original post?

thanks, bill

Reply to
William Oliveri

Well, what I mean to say is would the pickup distance make a difference that would effect/cause ping?

Reply to
William Oliveri

You mentioned in an earlier post that you hear your "ping" at idle, but not under load. If that's the case, I'd bet you're not hearing pinging.

Something else is making your noise.

Reply to
bllsht

I found that was not ping but some kind of belt noise I was hearing in the earlier post. Also, at that time, I didn't have the distributor set correctly becasue I didn't have an indexing pin when I first set it so it wasn't firing correctly. Since I reset the distributor I am now hearing ping. This is definitely ping and I don't hear it at idle but do hear it under load. Also, it's easier to hear at lower speeds than higher.

bill

Oliveri"

Reply to
William Oliveri

Reply to
Russ B

My MPI kit's pickup had a paper button on it. The directions said to place it right on the wheel, that the paper button was to wear away leaving the pickup at the correct distance.

Reply to
Jeepers

Black on one side of the white cone indicates bad or brand new valve guide seals... I'd guess yours are leaking. Sounds like you're talking yourself into putting that 4.0 head on... that's what Id do, were I you. I'd darn sure make sure that it was in fresh (read: rebuilt) condition before I swapped it in... big job. __ Steve .

Reply to
Stephen Cowell

Reply to
L.W.(ßill)

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