jeetS

1986 22rte 5spd.

A couple weeks ago the truck started not wanting to hold an idle. Id start it up in the morning, it would start fine but in about 20 seconds would stall itself out.

Wideband reads off the scale lean during these episodes.

At the end of my 1 hour commute to work I could usually talk in into idling by blipping the throttle a couple times ..but would be rough and lean.

Its almost like whatever tells the ECU that it is in idle and the RPMs are no longer being sustained by downshifting isnt doing its job.... what signals this??

TPS is in spec.
I just swapped in a spare, untampered with AFM and now the problem is worse. The old AFM had the mixture screw turned all the way in.

AFRs read normal at anything moderate load and up.

At very light cruise it will lean out almost off the scale and run rough


ANY Ideas???

MAINETOY

iTrader: (2)

Have you checked to see if the intake charge pipe rubber bellows are cracked causing it to be lean?Its quite common.Also check all other rubber connections for cracks and that they are clamped tight.

jeetS

Yes I've checked everywhere I can think of for vacuum leaks... that was the first thing I looked for.... It makes boost fine too...

Thanks for the input I'm open to any ideas!

bswarm

EGR stuck open?

jeetS

Thanks for the input^ I hadn't thought about the EGR.

Ill give it a few good wacks before starting the drive home.
Anyway to visually tell if its open?

bswarm

It's hard to tell just by looking at the EGR pintle, but it'll (the EGR valve) heat up real quick if stuck open. Also should not have vacuum at the EGR hose at idle. I can't find a vacuum diagram for the turbo model, but check the vacuum operated things, like waste gate, brake booster, etc.

jeetS

its strange... Most of the time if I bring the rpms up to about 1500-1800 while idling it richens up to normal 14.7 and smooths right out...

Its as if whatever tells the ecu that the truck is now in idle mode and it needs fuel applied is not doing its job (vs downshifting where fuel is cut)

bswarm

Any codes?

jeetS

I knew it was going to have some as its died a hundred times and that always throws something on these primative systems

I just reset the TPS for kicks, no change.

It wont Idle right so it wont drop into timing mode when I short the check connector.

It threw code 7 and 14...

14 really confuses me... its the overboost code. the 22rte ucu doesnt actually monitor boost level it uses a combination of the AFM vs TPS and probably RPM to determine if it is overboosting (I said primitive remember?) I do have a boost guage and it is nowhere near overboosting...


and for 7 the TPS has checked ok since the beginning... ill pull the EFI fuse and check again later on... Maybe some wiring has shorted between the TPS and ECU....

bswarm

The overboost code might be telling the ECU to cut fuel at low RPM's? That might be the reason it's having problems at idle, the ECU thinks there's boost when there isn't. Is the AFM for the turbo different than non-turbo? Maybe boost leak somewhere in the turbo or wastegate? I don't have and can't find anything on 22RTE diagnostic on the web, so just guessing now.

jeetS

hmmm interesting train of thought... If thats the case I wonder why it would only do it at idle.... Need to think more on this.

Yes the 22rte AFM is a different part #

Aside from the mechanical differences, the ECU, AFM, and injectors are different... Think thats it off the top of my head

jeetS

so from another forum:

Code 14 = fuel cut due to the ECU detecting too much boost. Fuel cut is determined by TPS angle, injector pulse width (how long each injector needs to fire), and how rapidly the AFM vane swings open.

Its definitely not overboosting. Set to stock = 6psi and im always monitoring my wideband and boost levels with in cab gauges

bswarm

How's vacuum at idle? Maybe if it's fluctuating it's playing tricks on the AFM. Does it idle ok with manual enrichment?

jeetS

So installed a good set of injectors ans checked a bunch of things today, ended up discovering that if you remove the plug wire to cyl#2 the idle wasn't effected...

Verified that that injector was firing and there was spark. Did a compression test and got 135-low 120s-135-high 140s (22rte so lower compression than 22re)

Bottom end of spec for 22rte is 120... Can't remember what upper end is but #4 is pretty high...

Hopefully it just needs a valve adjustment... #4 is quite high...

Will find out tomorrow if a valve adjustment helps.