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az chip wrote:I have nightmares about this Jeep and its timing. But seriously, this has been going on for so long I cannot remember every attempt at a fix. Has the MSD controller ever been checked by MSD?

MSD controller? Like the actual TBI unit? No they wouldn’t bring it back in for testing because they thought it was the HEI, which it seems to have been

Also, im glad im not the only one with nightmares about my jeep.

I'm going to snag a set of plug wire looms tonight and then see about making new wires in a week or two since i stupidly promised the set I have to the guy I sold the dist to. I didnt think about going to large cap and needing the HEI style wires.

Did a bit more testing and still got the same results.

Tested base timing. Locked it out at 15*, put light on it and it’s at 15* spot on. I couldn’t test at higher RPM because I didn’t have a helper to read the displayed timing. Will confirm that later.

Kept max timing at 30, dropped the rpm to 4K, got a ton of popping out the exhaust when coasting on the highway.

Left it at 5000 rpm and set max to 34*....same result.

30* at 5000 produces no popping from the exhaust other than the single decel pop due to the lean mixture.

I upped the vac advance to 10* and got a little popping. Backed it down to 8, and it went away.

It seems to prefer ported vac setting over manifold.

It’s running well and seems to be pulling good and strong.

Dr. Marneaus wrote:
It’s running well and seems to be pulling good and strong.

Give it what it likes...keep in mind changing timing does have an effect on fueling as well.

As a rule of thumb, if you advance timing, should give it a little more fuel.
If it's too lean, and advanced too much, you can get knocking(detonation) much easier, which is BAD.

Kinda depends on what AFR really means with the Atomic system...how exactly is their wideband calibrated?
How do they convert & display AFR on the LCD display?
What exactly is 14.5 AFR, is it a calculation based on lambda from the wideband, or ??
May want to research this some on the forums with folks actually running MSD??

If you're running e10, AFR settings would/should be different than real gas.
Most tuners these days use 14.1 or 14.3 vs. 14.7 when running e10.
You may want to use e10 AFR settings to see if it improves how it behaves, and responds to tuning changes.

I only have experience with GM TBI, LT1, LSx , and Ford 5.0/4.6 systems.
So can really only suggest things based on what I've learned w/ them.
Kinda flying blind with the MSD, but "should" behave similar?

One thing that jumped out at me was the popping through the exhaust. That's usually late timing or very lean mixture. I'm wondering if your outer balancer ring has slipped. I'd verify TDC with a dial indicator in #1 or #6 plug hole if it were me...

60 mile trail run today and it ran like a top.

Dr. Marneaus wrote:60 mile trail run today and it ran like a top.

That’s good!
Maybe finally getting it dialed in/gremlins vacated.

I’ve been driving it a bit.

None of the major issues from before. It’ll still occasionally hunt especially before the O2 sensor warms up, but it’s minimal by comparison.

None of the drivability issues are present.

I also raised the fuel pressure to see if that has any effect on any of it, as the instructions say it must have a minimum of 45psi. I know we think that is too much for the engine but I’m just trying to see if it has any noticeable effect

Personally I like running my ‘88 a tad rich, it has little more power, but mpg does suffer a ‘bit.

Now hopefully with ignition sorted out you’ll be able to tweak/tune to your likeing.

The jeep is RUNNIN'

Still getting the odd popping and occasional backfire. Apparently having no tailpipe can contribute to this as the back pressure can suck clean air into the muffler.

Aside from that, there have been no hiccups or drivability issues. I'm curious if my "eyeballed" phasing of the reluctor may be a bit past 15*, or a bit behind 15*, that few degrees could be making a difference here.

So, in an effort to keep moving forward, I made a few nagging repairs. I installed a larger pulley on my alternator so I can actually tighten it down properly. (yes, i know, this equals lower RPM on the alt, lower output, blah blah blah, it shouldn't be an issue I'm still seeing 14v at idle). This will eliminate the squealing belts and loss of voltage when headlights are on etc.

Then I went ahead and made new plug wires, and like some kinda professional, ran them in loom and separators. Got dang, it looks nice though! Next step for the coming weekends/evenings is to clean up the rest of the wiring from the EFI. I will be running everything in loom, and shortening a bunch of the leads that are way too long. Might go with a fuse block too, etc.
Untitled by Marn, on Flickr
Untitled by Marn, on Flickr

Back when i had a turn down in front of the rear axle on my old Cherokee, it would pop on engine braking like crazy. Soon as I added a tail pipe (to get rid of the exhaust fumes) the popping went away entirely.

Glad you seem to be getting things worked out

Victory! Glad to see that post. Cleaning things up is a sign the majority of troubleshooting is over. Keep on keepin' on!

Well, with the exception of the popping on low-throttle coast (which is likely caused by me not having a tailpipe), and the occasional backfire because MSD refuses to release a patch that offers fuel on deceleration above 2000rpm, this pile is RUNNIN'.

Been romping it around quite a bit, and there aren't really any weird issues or hiccups. It seems very calm and relaxed on the highway, and has plenty of power. Towed my trailer all up and down the mountains, no issues. Wheeled all up and down some crazy steep trails, no issues other than getting a bit warmed up. Nearly 200 miles on that trip offroad and towing, and I got about 10mpg. I'm not seeing ANY increase in MPG since getting the EFI, but we'll see, I havent been super careful about tracking it, but it seems like i'm still around the 10mpg average

Even a simple extension + a little turn down pipe on muffler reduces the popping...

If you want better HWY MPG play with higher AFR settings, but need to go easy, small changes and watch temps., and such.
Towing even with a small trailer is always going to kill MPG, 10 is actually pretty good for towing.

babywag wrote:Even a simple extension + a little turn down pipe on muffler reduces the popping...

If you want better HWY MPG play with higher AFR settings, but need to go easy, small changes and watch temps., and such.
Towing even with a small trailer is always going to kill MPG, 10 is actually pretty good for towing.

I'm, not upset with 10 combined towing and wheeling, just saying, i used to get 10 towing and wheeling.

Anyway, gonna put about 200 miles on it this weekend.

So, towing my little trailer around this past weekend, but mostly at about 60mph, I think I got close to 12mpg. I drove close to 200 miles and over the first 150 I logged about 11.8mpg

Thats exciting!

Nice. Glad you have found a point of equalization with the MSD.

Dr. Marneaus wrote:So, towing my little trailer around this past weekend, but mostly at about 60mph, I think I got close to 12mpg. I drove close to 200 miles and over the first 150 I logged about 11.8mpg

Thats exciting!

Between Bridgeport, CA and Reno, NV (115 miles give or take) I pulled in right about 12mpg while towing my little M416 loaded for camping. So, thats good.

So, still have very minor hunting issues, and the minor popping out the muffler issues, but otherwise the thing has been running great and normal. I haven't driven it much these past 12 months, but it fires up every time after sitting for months and pretty much just purrs. Nothing engine or EFI wise has failed me in quite a long time.