Help me rid this lumpy idle

[89PalermoSHP]

Ive got an idle that wont smooth out and Im wondering where to look. I hoped one of you could help me get this taken care of.

 

Things already done,

 

rebuilt engine, rebuilt throttlebody

new vac lines(checked a million times)

gm maf, maf-t(which helped a little but not enough)

new plugs gapped at .033(yes, ngk)

new wires, cap

new fuel pump/filters

my egr is hooked up but I capped the lines going to the canister

ive checked the 2 grounds on the intake and rebuilt them more or less

cleaned all of the other sensors leads on the intake

isc/tps reset

 

 

Ive got a new pick-up coil but I havent had the distributor apart nor do I think Im smart enough for that. Id like to get the entire thing rebuilt but good technicians seem to be rare around here.

 

Any thoughts or advise is appreciated

Edited July 20, 2008 by 89PalermoSHP

[Komeuppance]

Leaky injector??

 

-Robert

[Goddard]

You say you capped the lines to the charcoal canister. The gas tank vents to the canister then the fumes sucked back into the intake I believe. Maybe without the vac lines going to valve above the canister, the gas tank isn't being vented properly. I have the vac lines operating the valve on my car with the egr blocked off. I can get a diagram going if you'd like. I think it would be helpful to many members here.

[Indiana]

your plug gap is very small, increase it to .036-.038 and which ngk plug did you use? 6s? 7s? and they aren't blackened are they?

 

how about a new coil?

 

is the compression even ?

 

hows the fuel pressure? you have an air fuel gauge? narrow band should show pretty rich at idle

 

is the rpm even or does it surge up and down?

 

unplug the CTS, did it change?

[89PalermoSHP]

Thanks for the replies, my internet has been down the last 2 days so....

 

I knew Id forget some things,

 

I will open up the gap on the plugs Friday. They were brand new as of last Sunday.

 

Coil is a new msd blaster2

 

Not sure on the fuel pressure... EVERYTHING is new from the tank filter to the injectors, injectors were cleaned and flowed and returned as "excellent". I can scan the test results if they would help. The regulator is newer but not new or oem.

 

I have the aem uego for a wideband. Im showing about 12.9 idle, mid 14's partial accel, and wayyyy rich on heavy accel/wot. Im still working on the maf-t settings. One thing I notice is when Im at a stop in drive it idles at mid 14s but if I shift to neutral it drops to 12.8ish???

 

The rpm never really surges but I notice it will stay at 12.9ish and then jump to high 14s/low 15s for a second or two than back. It will do this every minute or so. Im going to do a tps reset on friday as well.

 

CTS is a brand new OEM unit. It made a HUGE difference but this was before all of the fuel pump issues.

 

Im sure Im still leaving other stuff out but after my 3rd 12hr day, Im a little short on brain power. Ill update friday afternoon.

[Shelby]

ok first thing youhave todo is a compression test,, new engine or not this is info you have to have,, even or very close comp will give you an engine that will idle smooth,, any large veriation in comp and a smooth idle is imposible,,

 

improper valve lash , not sealing valve seats, weak springs etc can also effect the idle

 

next is fuel pressure,, you need to know for a fact what it is,, guessing don't acomplish much

 

leaking injs,, take the time to visualy inspect them for leaks under pressure and for the full time it takes for the fuel system pressure to bleed off,, many times an inj will not leak under full pressure but may at diff temps during the cool down cycle,, this can take 30 min to well over an hour so don't be in a rush

 

now are you runing larger injs then oem specs, if so you will have to have a way to trim the fuel mix back down for idle mixtures ,, this is not always easy to do and takes a lot of time , trial and error

 

vacuum leaks if you can try to find out what cyl is not fireing even, then check corosponding intake runners for air leaks , do not over look the brake booster or hose

fuel mix problems will seem to move from cycl to cyl and not be any one cyl ,

rich and lean will apear to have the same symptons on a fuel inj engine it's very hard to tell the diff , altho you can create an air leak if the mixture is real rich and help the idle , the pcv hose is a good one for that as it's in the center of the cyls

 

what you'l need to concentrate on depends on if the engine is lean or overly rich,, that is some thing you'l need to find out, then go from there to find a way to correct the problem

 

it may be nessarry to remove recent mods to help pin point the problem area

[89PalermoSHP]

thanks Shelby,

 

Compression test was(front to back) 120,115,120,120. I really hope its not a ring issue... The entire head was new, head, valves, schnider springs, cam(stock replacemnt),rocker arms(new oem), rocker shafts, springs, wavy washers... everything. the head is a marnal assembled by dad(valves/springs anyhow).

 

A fuel pressure gauge would be nice. Id like to get one sometime in the near future.

 

Injectors were cleaned/flowed and do not leak as far as I can tell. They are stockers that were in good condition before the clean.

 

At the moment the engine runs rich for the most part. It seems like the auto makes it more complicated to get the numbers right. This is my first time doing this and Im thinking about getting it done on a dyno.

 

Really the only mod I have is the gm maf/maf-t and the bypass valve. I went back to the stock turbo as well.

[Shelby]

why did you go to the GM mass,, you gain nothing with out larger injs

put the oem mass back on and go from there , a 1G air mass would be of more use then the GM mass for a stock system

 

your comp is a bit low but lots of things figure into that , several of my engines have all been 120 lbs even when new , and i find 120 to be more inline with 7:1 comp then 145 lbs

altho as far as i know my truck eng is stock and has always had 145 lbs across the board ???

[89PalermoSHP]

I do have the wisecos but I did not get the higher comp ones from Dad.

 

I got the maft so i would be able to control the fuel but Im trying to figure out the base setting as I am running rich as heck on wot.

 

Maybe I should throw my 1g mas back in for chits and giggles... see what,if any, changes happen.

[John86TSi]

Speaking of the PCV hose as Shelby said, are you using an old PCV valve you had from before the engine rebuild? They are cheap on Dad's site so why don't you try a genuine Mitsu PCV valve to see if the problem is there for idle?

 

For troubleshooting, you could unscrew it and plug the end that screws into the valve cover. Fire the engine up and see how it runs.......

 

BTW, I have an 86 that idles lumpy too. I have changed out quite a few items, still have not smoothed it out like I like it. I am gonna check some of the other things Shelby said in the thread, he's a pretty smart feller!!!

 

John86TSi

[Caliber308]

A fuel pressure gauge would be nice. Id like to get one sometime in the near future.

 

No Fuel Pressure Gauge????? And i'm guessing no Adjustable RRFPR either???? SHAME ON YOU. With the primary/secondary injector set up i'm running, I had to lean the s--t out of my MAF-Translator at WOT. Mine idled like crap intil I installed a Three-wire 0-2 sensor. The 0-2 (heated sensor)kicks in sooner and the car idles fine after initial cold start up.

 

CALIBER 308

Edited July 19, 2008 by Caliber308

[Technology]

If you still have jet valves theck that. Any vacuum leak could cause a problem, how about the "4th" port - the single one below the 3.

 

Also, have you done a boost leak test. A tear in the boost tubes might cause probs also.

[89PalermoSHP]

Speaking of the PCV hose as Shelby said, are you using an old PCV valve you had from before the engine rebuild? They are cheap on Dad's site so why don't you try a genuine Mitsu PCV valve to see if the problem is there for idle?

 

brand new valve, brand new hose.

 

no jet valves(marnal)

 

Yes Cal... I need a gauge

 

1g mas ive got is either crap or something because I swapped it back in and it ran worse.

 

Cal.. what setting do you have the AUX switch on the maft? I dont understand the table in Appendix A. What number combination am I looking for using stock injectors? AUX 1-4 and BASE 0-9/A-F?

 

It wants to run well but it richens out hardcore at hi-mid to wot.

[Caliber308]

brand new valve, brand new hose.

 

no jet valves(marnal)

 

Yes Cal... I need a gauge

 

1g mas ive got is either crap or something because I swapped it back in and it ran worse.

 

Cal.. what setting do you have the AUX switch on the maft? I dont understand the table in Appendix A. What number combination am I looking for using stock injectors? AUX 1-4 and BASE 0-9/A-F?

 

It wants to run well but it richens out hardcore at hi-mid to wot.

 

AUX to 0.

BASE to 0.

Mode switch 1 and 2: OFF/OFF.

 

On your IDLE, MIDRANGE and WOT, It's a guessing game according to your engine and modifications. P.S. At WOT, just lean it out according to your Wideband reading.

At IDLE and MIDRANGE: Adjust accordingly to your Wideband readings.

 

CALIBER 308

Edited July 19, 2008 by Caliber308

[Shelby]

ok lets get this non oem stuff off the car untill it runs 100%

NEVER DO ANY MOD TO TRY AND FIX A PROBLEM all it'l do is complicate things to a point you can't tell if you found the problem or not

 

your car will run 100% with out any mods or air mass changes

 

you can take note of Cals setings but don't use them right now,, put your car back to oem and get it runing perfict , then go play with toys

[89PalermoSHP]

That is solid advise Shelby, unfortunatly the 1g mas made it run worse and the stock mas has too many things missing now to be useable I think.

 

I understand completely what you you mean though...by putting a bandaid on an issue(like installing the maft) Im introducing too many variables.

 

Im starting to wonder if it will ever run right. Ive got a feeling its a broken wire in the middle of the harness halfway into the firewall(worse case scenario like most other issues Ive had)

[Shelby]

i've been doing this for a good while andone thing i have never found is that broken wire in the middle of a harness , now a broken wire where it is flex'd a lot yes

 

don't think of the imposible you'l have more luck thinking about the ovious things

and looking at means more then just LOOKING at

[89PalermoSHP]

Well... Im getting alot closer with the maft settings. The numbers are starting to look like they should and the motor isnt bogging down. I had to lean the heck out of the top of it and Im trying to tweak in the middle.

 

The wire thing was more of a "just my luck" kinda thing. Seeing as I dont have any real mechanic knowledge other than the obvious, Im kind of learning as I go. It really helps having everyone heres input and suggestions. Thanks again everyone.

[89PalermoSHP]

Ok... I did a compression test today and Im(me personally) about to blow a gasket...

 

Front to back... 140,70,140,140

 

Im guessing theres 2 issues that would case this, the head or the block/rings. What is my logical next step before I take the shop to court? Its the same cyl that checked low a year ago when I tested it but it was only about 5-10psi lower than the rest at that time.

[mikec]

First, figure out WHY the cylinder reads low:

* bad rings

* one or both valves not sealing correctly

* jet valve (if you still have them) not sealing correctly

* head gasket sealing issue

 

How to figure out the problem:

* Remove all 4 spark plugs. Leave the valve cover ON, remove the oil fill cap. Remove the over-the-valve cover pipe to the throttle body.

 

* Rotate the engine until that cylinder is at top dead center. The timing notch on the crankshaft pully will be 180 degrees opposite the "T" on the timing chain case cover when cyls #2 and #3 could be at TDC. As you rotate the crank pully (clockwise only as you face the front of the engine) put a cork in the spark plug holes of #2 and #3. Whichever cork pops out and flies across the room is on its compression stroke - turn the crank pully until the #2 cork pops out. Then line the pully so the timing notch is 180 degrees out of phase with the "T" mark. Put a stick-shift tranny into 4th gear and set the parking brake to lock the engine. Put an auto tranny into Drive... it help hold the engine but it won't lock it. Leave a breaker bar/wrench on the crank pully bolt, jammed against the garage floor to help hold it.

 

* Hook an air pump or air compressor set to about 10 to 20 psi to the #2 spark plug hole. You'll need a rubber cone on the end of the compressor hose to shove into the hole.. or use the threaded end from your compression guage and hold the little "pressure release" pin down while you do the next steps (hold it down with tape).

 

* With air going into the cylinder, listen/feel for where it's "leaking" out:

1: out the oil fill opening? Ring issue. Repeat the compression test after dribbling about a spoonful of oil into the #2 spark plug hole; if the compression numbers increase 20 or more psi then that confirms a ring issue.

 

2: out the exhaust pipe? Exhaust valve isn't sealing properly

 

3: out the throttle body inlet (where the over the valve cover pipe connects)? Then intake valve or jet valve.

 

4: bubbles visible inside the radiator? Cracked head, cracked block, or cyl head gasket issues.

 

If it's a valve issue, shut off the air compressor and then remove the valve cover. Loosen the bolts holding the rocker arms, rocker shafts, etc. almost all the way - enough so the rocker arms on cyl #2 flop around. Watch for the little medicine-pill shaped auto lash adjusters in the ends of the rocker arms - they'll want to fall out if the rocker arm and valve top get too far apart. Wrapping tape around the ends of the rocker arm, or slipping cut-off fingers from a rubber glove (i.e. like condoms) over the rocker arm ends are typical tricks to hold the auto-lash adusters in place.

 

Now turn the compressor back on and see if cyl #2 no longer leaks air out the intake or exhaust - i.e are the valves sealing properly now? If the valves DO seal properly then either your lash adjustment (if you have the lash screws) needs attention, the camshaft is mis-ground (unlikely), the auto-lash adjuster is jammed (common if metal or plastic bits ever circulated through the oil, when jammed it acts like a lash screw that's turned all the way in), incorrect valves (early model year valves were longer), incorrect ratio rocker arms, etc. SOMETHING was holding the valve open leading to lousy compression.

 

Note: when loosening (and re-tightening) those rocker shaft bolts... do them about half a turn each and then move on to the next one. Do NOT totally loosen one bolt and then move on to another one - do all of them together. This minimizes uneven stresses that can warp/damage the rocker shafts. Just like when you torque the cyl head bolts - do each one part-way, move on to another, and another... eventually coming back to the first one and going a little tighter on it until all are torqued to specs. Torque those bolts to 15 ft-lbs using a SMALL torque wrench - not your average half-inch drive monster. It won't be accurate at such low torque settings.

 

mike c.

[89PalermoSHP]

Thank you Mike for your input. Im thinking I might be better off to take it to someone a little more qualified than I. If it is an issue that was caused by the shop who rebuilt it, I dont want to be messing with it and possibly adding to the problem. I thought a professional diagnosis would be best if I stand any chance of recourse.

 

Just out of curiosity, what would the condition of that cylinder do to the overall a/f ratio(as read by the wideband 02 sensor-AEM UEGO)?

Edited July 20, 2008 by 89PalermoSHP

[Indiana]

is the head used? a bend spring, worn guide, a valve that was bend before now bend more,

 

a bent spring wears the guide and valve, the valve tries to seat but its tilted and sort of seats then will get better as it revs up but still have problems, that puts irregular wear on the seat and valve so it may not be a rebuild problem it could be a bad part, the guide or valve or seat I mean

 

if you have no excessive crankcase pressure, no water being pushed out its likely something in the valve train

 

a cracked ring may have low pressure in one cylinder

 

do the plugs all look the same? the cylinders still fire and burn just not as good

 

for example, a dohc dsm that breaks the timing belt, someone replaces it and the motor still runs, it sounds like a click clack unoiled clock but it still runs and it may not smoke but that is a valve train issue and its bent valves

 

you hear some click that sounds like a lifter loose?

[89PalermoSHP]

The head and EVERY SINGLE component in it was brand new. Everything. Every single thing above the block was brand spanking new. It was assembled(valves) by Dad. The cam, rockers, and rocker shafts were installed by the shop who rebuilt the motor.

 

How could I tell if theres excessive cc pressure? Theres no coolant loss, ect..

 

A cracked ring would be a good thing I think at this point providing it could be changed w/o removing the entire engine.

 

All the plugs looks fairly the same but again, they were new less than a week ago. I can get a pic of the ones that came out although I dont quite remember which was in which hole. The cylinder still fires yes but not the same as the others apparently causing the rough idle. This was apparent from the day I picked it up from the shop. There were so many other things that needed attention(like resetting the tps/isc, replacing the USED CTS they put it, the fuel pump issue and for all I know they are the one who crushed my fuel line) for me to consider that the bottom end wasnt done properly.

 

There are no clicks coming from the head at all.

 

At this point I think I need advise on a professional diagnosis and to determine why this motor will not run correctly. Ive put a total of 1200 miles on this, changed the oil more times that I can even think, and done everything possible to break the motor in correctly. I cant see how they could have properly sealed the rings in the first place when the motor has run like crap from the get-go- again they put a USED CTS in which I doubt was from a quest, the tps/isc wasnt set properly since Kelly completely rebuilt my TB while the engine was getting done and I KNOW they did nothing more than bolt the intake back on, the fuel delivery issue, the fact that they didnt drain the 2 year old gas that was in the tank only added 8 gallons to it even though I asked them to change it. I think the motor was doomed to fail from the start. I made a big mistake taking it to these guys and it was something I didnt realize until it was too late. Ive got a ffeling that there needs to be some serious work done to the motor and I dont want and shouldnt have to pay for again. I need to know the best route to take to (professionally)determine whats wrong and whos fault it is so I can have a leg to stand on if this has to go to court. I know the shop wont do the stand-up thing and fix their error.

[Shelby]

lots of guess work going on it seems,, a simple leak down test will tell you where to go next,, odds are it's a burnt ring land or broken ring , but a leak down will point to that and not some thing in the head

 

at this point it's useless to be placeing blaim , if it's a bad piston and the bore is stock, it's a simple matter of swaping in another piston, and keep on going

 

old gas will not distroy a piston, you can easily break a ring durring install, been there done that many a time

 

one good over heating spell will some times cause a ring to be pinch'd and from then on it's only a matter of time till the ring land burns out

[Dad]

Ok... I did a compression test today and Im(me personally) about to blow a gasket...

 

Front to back... 140,70,140,140

 

Im guessing theres 2 issues that would case this, the head or the block/rings. What is my logical next step before I take the shop to court? Its the same cyl that checked low a year ago when I tested it but it was only about 5-10psi lower than the rest at that time.

 

 

Friday, you had 115 lbs?, you sure that you did not get a Bad reading? I would retest, it doesn't drop 45 lbs overnight.

 

See if you can locate a leakdown tester. that can tell a lot also.

 

Dad