CIS runs bad now

[klaucke]

I'm having trouble with my 1974 2.7 with CIS
I took the CIS off a couple days ago, to replace the boots which were cracking. I made a list of everything I disconnected, and made sure [multiple times now] that I reconnected everything. However, the engine runs like crap. It backfires a lot and has no power. I can't figure out what is wrong.

Like I said, all I did was take the CIS off [with engine in car, wasn't that hard], replace the boots, and put it back on. However, while it was off it was turned vertical when I replaced the boots, if that could have some effect. And also, I lightly pushed up the metering plate, or what I think is the metering plate, with my finger [the movable plate that is in the top of the airbox, accessable from below itself]. Could moving this without the plate have cause a problem?

Before I took the CIS off, it ran mint. It started on the 1st revolution, and had plenty of power and pep. Any advice would be greatly appreciated. I've gone through all the connections many times... and everything is connected. Help!

[Hladun]

Air leak somewhere.

[klaucke]

I can't see how there would be an air leak... all the boots that connect the airbox to the intake runners are new, and the hoses that go to the airbox; just the oiler filler breather and a hose from the fuel accumulator [I think that's what it is, the canister attached to the fire wall in front of the engine] which are good and tight.

Sometimes if I rev the engine a bit, when it runs, it will say up in RPM's when I get off the throttle. Does it sound like a problem with the metering plate adjustment? What could have gone wrong?

[vash]

do you have the CIS testing pressure gauge? i think you have to test system pressures everytime you do something major to the CIS system. my guess, from the description, sounds like it is running lean, or you have a vacumn leak somewhere.

[jdowty3]

How long have you let it run? It takes a while to get all the air out of a CIS system, which makes the motor run very lean and backfire a lot. If it's not that, then "unfixed" has the right idea.

[stlrj]

You might just have to take it off again and start from scratch. I've been in your situation many times and I know what a PIA it is to do all over again but I always found my problem and it usually turned up being something stupid that I overlooked.

Cheers,

Joe

[klaucke]

I let it run long enough to purge the system of any air, and long enough to get scared at how it was running. I took it for a quick stroll down my street so I would think it was enough to purge the system.

I'd like to think I didnt' overlook anything, like I said I made a list of everything just for this reason, and I marked down everything!

I would do the test with the pressure guage, but I don't have one, and before I removed the CIS it ran mint. I dont' think just changing those connecting rubber boots is major, is it?

[vash]

the gauges would tell you right away if you have any component issues.

[Dr. No]

Obviously, your car had been adjusted to run with an ait leak that you have now corrected. Try loosening the manifolds.
Or something loosened on return to the vehicle--get a spray bottle of water and squirt around the boots, manifolds, etc. with the engine warm and running and listen for stumbling. If that doesn't help get out on the road and run it more than a few blocks, you may have loosened up some crud in the fuel and need to clear it out.

[klaucke]

I just took the CIS off again... everything looks like it was fine. I am super bewildered. I think that Dr. No's advice may be the only remedy, that is was adjusted when it had air leaks, which now without leaks is maladjusted. But, if it had leaks at the intake boots, wouldn't you richen it up to compensate? Now it backfires, indicating it is too lean. Oh, and how badly I wanted to take it out this weekend...

[bigchillcar]

ah...dr. no...we meet again...

yes, i agree with dr. no (did i really say that?)...if it was running great with the air leaks before, the mixture must have been set to compensate. i would check the percent co now...it's probably no longer set to spec...
ryan

[klaucke]

I'm not saying there *were* air leaks before, I just wanted to fix the boots before they became a problem and possibly caused the engine to run lean/hot. So I don't think there were large air leaks in the system. I tried adjusting the adjustment screw that is between the air boot on top and the fuel distributor, but it doesn't seem like it wants to turn. Any tips?

[bigchillcar]

i'm assuming you're using the 3mm allen wrench...it can be tough to turn, actually...mine is a little stubborn. i would try quarter turns and check. for that matter, what is the condition of your spark plugs? these can tell the story of how your mixture has been for a while. are they more on the whitish side? or more on the black or oily side? if brownish, your mixture is probably fine.
ryan

[Hald]

Is it possible that the problem has nothing to do with the CIS? Perhaps while working on it, you caused a disconnection in the ignition system - like the coil wire, one or more plug wires...

Just a thought.

[klaucke]

The plugs looked fine when I took them out a week ago, which was directly prior to taking the CIS off for the 1st time. The odd part is, I had the CIS off once way before when I fixed a broken piston over the course of the last two months. Luckily it ran great when I put it back on, but then I took it off to fix those boots.... no dice.

All the electrical checks out. Points are clean, gap is right, and timing is right on. I checked and rechecked my coil/sparkplugs wires. I'm getting very lost here.

[klaucke]

Also, when I say I can't turn the adjustment screw, I mean it doesn't want to turn either way with decent force. The 3mm allen is starting to twist, and there is no movement. Wayne's 101 tips says there should be adible clicks... I'm having no luck here.

Can the WUR just break like this? If I dropped the #2 intake [which I didn't]?

[Jim Sims]

Don't keep guessing - you're depending on luck and you may end up unnecessarily replacing very expensivce parts. Get a trouble shooting guide and a pressure test harness and start systematically going through the guide. A CO analyzer is needed to properly set the mixture. Oh by the way; if properly maintained the CIS fuel injection systems can run well for decades and many 911 systems have.

[klaucke]

No need to guess.... like I said I took the CIS off again last night, and I just put in on again now. I was extra methodical and made sure to tighten everything evenly and squarely. Well, it did the "run like crap" routine for a minute, then she smoothed out to the grumble I'm used to. Woohoo! I got her back for this gorgeous New England weekend! The only part I dont' like is not knowing what the problem was, since I went through everything. However, I am now extremely proficient at CIS removal without even lowering the engine- I can do it in about 30 minutes while still going slowly.

[Hald]

Congrats - just in time for the great weather!

[Gunter]

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Quote: Also, when I say I can't turn the adjustment screw, I mean it doesn't want to turn either way with decent force. The 3mm allen is starting to twist, and there is no movement. Wayne's 101 tips says there should be adible clicks... I'm having no luck here.
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I would look a little closer at the mixture adjustment screw. Even though it runs o.k. now, at some time you'll need the adjustment. It should turn relatively easy, not all of them click. If you are sure that the long 3mm Allen engages and you cannot move it, try spraying some WD40 onto the Allen key while it is in there so that the lubricant runs down the key and onto the srew. Then try moving it either way just a little. Remember to remove the Allen when reving the engine.