Why pinging returned after new EGR and TFI?

[tito]

Last year about this time I installed the Anti-knock kit from the dealer(new EGR and vac hose links). The pinging went away, but I did the TFI conversion as an extra bonus. The Jeep went to Invasion 2003, all Summer, Fall and Winter with no pinging while running on 87 octane.

Now the pinging is back. Here's what trends I've noticed.

- No pinging at all when first started up and driven.
- Pinging mostly happens between 1/4 throttle and 1/2 throttle. Under or over these positions is okay.
- The longer it's driven, the worse the ping. Sometimes even off the line at a light, it begins to ping.
- There's no consistency of how long to drive before it starts, sometimes 1/2 hr, sometimes and hour or more
- Higher octane helps, but not completely

Any ideas?

Thanks,

[PhilSine]

Adjust the timing until it stops pinging and call it good. Before you do that check the EGR system out again to ensure its functioning properly.

If the upgrade in the ignition correlated to the pinging then my theory would be that because of the added efficiency of the burn it is now causing too much fuel to burn too soon with respect to the timing.

You did the EGR a year ago. Did you do the TFI recently or back when you did the EGR?

[ March 02, 2004, 03:09 PM: Message edited by: PhilSine ]

[89grand]

When was the last time you checked the igntion timing? If it's been a while I check that first.

[tito]

Thanks for the replies.

I did the TFI about a month after the EGR/anti knock kit, which would make it last April. That's what's confusing, it ran great on 87 all summer in the 90+ degree and humidity after both mods. Until the last few days, it's been cold for us. I can only imagine what it will sound like when hot weather returns.

The EGR is not seized, but I'll check it again. The timing was 12 degrees TDC when the TFI was done last April and it hasn't been checked since. I guess it could have slipped in the last 6 weeks, but don't know why. It fires soon as I hit the key almost everytime, wouldn't slipped timing make it harder to start?

All ideas are appreciated.

[89grand]

Well the other morning I started up the Grand and it was ticking super loud, I shut it off and opened the hood to check it out and my distributor was so loose that I could just turn all over the place by hand. I'm not sure how that happened but it's not impossible that your distributor could be jst loose enough to change the timing. Either way, I check it, if it only advanced a few degrees you would still be able to start it.

[tito]

Steve, thanks for the reply. Dizzy bolts and timing are the next things to check.

Ater reading some other posts, seems there's a list of possibilities - carbon build up, weak dizzy springs, timing chain, etc. I guess with 166K miles, it could be anything now. Although I'm wondering if the motor was rebuilt before I got it.

[Knucklehead]

Sounds like your getting a lean condition. At 1/4 -1/2 throttle your carb is not metering gas at the right rate for the vacuum the engine is creating.

The egr introduces exhaust back into the manifold to help prevent knocking (by cooling down the combustion temperatures and slowing the combustion process). This allows the carb to run leaner without knocking, when it all works correctly.

Most likely, you got a problem with the egr, but could be the carb and/or timing as well. Check timing at idle and 2000 RPM. make sure your full advance is where it should be (about 32-35 degrees, you better check as I don't remeber exactly). If that is correct then start looking into the egr and carb.

[1BDWAGN]

If you think it is carbon build-up I use a product called seafoam (Napa carries it) to help loosen deposits. It's one of those cleaners you pour down the carb slowly then dump the last of the can quickly to kill the engine wait 5 minutes or so and bask in the smoke billowing from your exhaust pipe when you start it. It's good for finding leaks in the exhaust around the manifolds.

[89grand]

I've been meaning to try that Seafoam stuff. Can it clog the cat though?

[Ralph]

Pinging can be caused by a lean-running condition, as well. A tired fuel pump, for example, may cause a lean condition under load.

[1BDWAGN]

Steve,
I honestly couldn't tell you if it would or not. I have never pulled the cat after doing it to check. I would think if your 360 has been neglected there may be a lot of chunks that would come free and may block some of the catalyst substrate but with a truck maintained like yours I don't think you'd have to worry about clogging.

[letank]

make sure you CTO are working properly.... you may have manifold vaccum advance..... i would disconnnect the vacuum hose at the distributor and plug it.... this is a quick check

happened to the 85 Gwag

Michel

[tito]

Woohoo, I hit the motherload on ideas, thanks guys. :D

66HD - I'll check the EGR lines again for leaks and now I remember a new PCV was the first attempt to correct the ping. What would cause an EGR problem other than clogged up or vac leak?

Also, checking the full advance timing, how is that done? On an '87, idle timing is checked while in gear. I don't much fancy the idea of crawling under the Jeep to get the timing light on the crank while it's revved to 2000 rpms.

bd2thbnAZ - I've heard of Seafoam, but never knew what it was for, thanks for the idea. BTW, got rid of the cat last year with the EGR/TFI mods, so no chance to clog here. It should also help me find that manifold leak = extra bonus.

Ralph - The fuel pump idea is suddenly making sense. Every morning, I start it, it runs for 5 seconds and quits, I start it and it stays running. Wondering if a weak fuel pump is losing pressure when it sits and the initial morning stall is from a bubble in the line? The pump could be starving the engine. I carry an extra in the tool box, guess it will go on now.

Michael - Thanks for the idea. I checked the lines for leaks, but didn't think of all those CTO's possibly being bad.

Sounds like the ususal Jeep, one problem and a dozen possible causes. Thanks for the help guys, can't wait to get home and bust some knuckles.

:cool:

[89grand]

Just for the record, you don't have to get under your Jeep to set the timing, you point the timing light through a space near the alternator bracket in park. To check your total advance you'll need a timing light that has a dial that lets you check total advance. I've got one. You rev up the motor until you reach maximum advance then adjust the dial until you see the timing mark again and read the dial and that is your total advance i.e. if the dial reads 35 degrees than that is your total advance.

[tito]

Steve, thanks for the xtra info.