Low RPM/idle with Lh2.2 and fully built motor??

[gottarollwithit]

We just swapped in a fully built/upgraded motor and the idle is rough and shaky. The idle AFR is about 15.1. When driving under 2k RPM in 1st, the car bucks b/c the engine speed is unable to hold or smoothly go up/down. So, if i drive slowly, i can feel the car jerking b/c the engine speed is very unstable at low RPM. When at higher RPM, it's fine though. If i shift from N into D or N into R, sometimes the engine dies as i click it in gear.

Any ideas why this would be occurring?

Granted, the RSI Stage 1 cam and using Dale's underdrive pulley probably aren't helping the idle, but that doesn't really explain the jerking at low RPM.

Outside of an MSD Blaster coil, the ignition system is stock lh2.2. I just cleaned the IAC and it didn't help. Before the swap, everything was working perfectly fine...

Any ideas???

[andysbeta]

So the IAC is trying to regulate @ 750 RPM with that cam in it? Probably not going to do it - the cam is probably just too much for LH2.2.

How is static compression?

[gottarollwithit]

I had the cam in with a stock motor and it was able to idle ok. The idle was lumpy b/c of the cam, but it wasn't nearly as shaky and rough as it is now. It's so shaky that it's making my muffler rattle around on it's bracket!! I upped the idle RPM to around 900 to try to smooth things out. It's still pretty shaky and rough.

Never tested compression. I think that'll happen soon though.

At the moment, i think i'm pointing towards this being a valve clearance problem b/c the valves do break in a bit after the initial use of the motor.

Thoughts?

[andysbeta]

Oh, okay.

I wasn't sure of how much lift that cam has but if it previously did as you said.. then I'd look into doing compression test and as you mentioned.

Probably valve clearance as you say, a cylinder a bit too low on compression and the new build all conspiring against another. So above 2k rpm the motor generally behaves okay?

[klr142]

Check the valve clearances and loosen them up to .016" at the tightest, if any are tighter. Verify all your ignition components are still in good shape, wires are tight and the plug gaps are good.

If it continues, it wouldn't hurt to check compression.

[RvolvoR]

check that you dont have the tps and iac plugs swapped....

[andysbeta]

Oh yeah, that is a good thing to check indeed! Mixing up TPS and IAC will do that for sure. I've been there and done that myself.. with results as you are experiencing.

I burnt up the IAC circuit on a LH2.2 ecu by making that mistake once.

[RvolvoR]

Originally Posted by andysbeta

Oh yeah, that is a good thing to check indeed! Mixing up TPS and IAC will do that for sure. I've been there and done that myself.. with results as you are experiencing.

I burnt up the IAC circuit on a LH2.2 ecu by making that mistake once.

the jerking while driving is what led me to thinking that this is what he has going on....

[gottarollwithit]

How can i tell if the IAC plug or the TPS plug actually belongs to it? I don't think we ever unplugged either b/c we never fully removed the intake, but I want to make sure that both are plugged into the right wires.
Will switching them for a few min hurt anything?

[cosbySweater]

what about the valve on the bottom of the throttle body? you mess with that at all?

[gsellstr]

The TPS and IAC both were unplugged when I got there for the swap Brian. Any chance someone has the wire colors off-hand for one or the other? I thought about that, but it seemed to behave pretty well when I was there, plus the wires seemed comfy when I put em back on, but it's certainly still a possibility.

Also the valve clearance and compression test are definitely on the list for my next trip over there...

[dragbrick780]

It wouldn't hurt to make sure the cam timing is on spot. Being to far off could cause similar symptoms.

[gottarollwithit]

Dang, it's not a case of IAC wire plugged into the TPS or vice versa. The TPS wiring loom has a sheath around it and the + wire for the starter. The TPS/starter wiring loom can't physically reach both the IAC and the starter without cutting the sheath apart.

As for ignition timing adjusted by rotating the dist, i've went +/- from about 10 to 14 deg and it does help a little bit, but not much. Retarding or advancing too much just makes the idle even more shaky.

Any other ideas?

[andysbeta]

A quick way to check for IAC and TPS is to get your volt meter..

The IAC should be putting out +12vdc on the pins while car is running (unplugged of course). TPS will have +5VDC on it.

If you wanted to be double sure that is what I always do when I replace or install a LH2.2 harness these days.

I'd suggest a compression test, easily done.. Get the baseline first!

[nx3xo]

What ecu and ezk are you running?

[gsellstr]

Stock LH2.2 stuff. The car was smooth before the engine swap, I'm thinking the valve clearances sound about right for the issue.

[gottarollwithit]

I'm just wondering what the heck else could be causing this.
Outside of a full engine/trans swap and a new blaster coil, everything else that was working just fine before the swap is still being used.

[ZVOLV]

Did you adjust the mixture, set the idle, and adjust the throttle body AND TPS?

Maybe PM coupedgrace. He did a 2.2 engine build and I know he had idle issues. Not sure if he got it fixed though.

[gottarollwithit]

That was an initial thought b/c my idle mixture is a little bit leaner than it was before, but i was thinking that the mix could be off as a result of other problems.
After we look over the compression and valve clearance, i'll dial in the AMM. Getting the idle AFR corrected via the AMM really won't help much though.... The difference that half a point makes is practically imperceptible.
Is the TPS adjustable? I used the big thumbscrew to dial up the idle speed to try to smooth things out. Is that what we're talkin about?

[ZVOLV]

You gotta make sure ALL the adjustments are just right on the throttle body and THEN adjust the TPS to that. If somebody has gone in there and the stop screw, throttle linkage, TPS, and idle screw have all been tampered with, it won't idle right.

BTW I hate LH2.2. Why build a complete engine and run it on 2.2? Are you gonna run stock injectors? ( If so, what's the point of a built engine.) Or put in bigger injectors and hack the MAF signal?

[MrBill]

Verified no air leaks? MAF confirmed to work?

No way its the cam. Stage1 might as well be stock

[gottarollwithit]

Couldn't be any air leaks. We're using the same hoses as were on there before, which were just fine. I even went on a vac leak hunt and came up with nothin.

The MAF is good. Twas workin fine before the swap. Just for kicks, i guess i could unplug it and see what happens.

The RSI cam indeed does give the car a loping idle, but it's not supposed to be this bad. What really concerns me is the unstable engine speed at anything under 2k rpm. If i try to hold an engine speed under 2k, the rpm's just kinda flutter.

[cosbySweater]

your cam adjust would have to be sooooo far out of wack for it to do what your describing

[gottarollwithit]

My cam adjust? What are we referring to here?

[cosbySweater]

valve adjustment
sorry