Step Side 88

Just the facts Ma'am...
88 22re 57K miles.
Normal drive is 5-20 mi @ 45- 60mph @ 55 - 68*F (90% of the time)
No codes @ T-E1 other than ok.
TPS in Specs per FAM
AFM also tests OK per FAM
No vac leaks detected

Now the story.
(Note: These same symptoms happened last year during same weather pattern)
Weather here is as stated Pacific ocean controlled temp 90% of the time. And as stated the truck usually travels 20 mi RT tops.
Those are the variables I can see at play.
So mid dec. the temps took a dive into the freezing rain and snow in the mountains range and of course, I needed to take a drive for a tool sale savings spectacular... it was something I wanted/needed and there was only one place.
So I had to go.
I head out over the coast range and reach the flats of the valley and everything is ok cruising as fast as allowed.
8 or more miles to the first town and the first speed zone of 35 mph and the engines sputters and stalls.
It restarts with difficulty but once rpms get up and I drop it in drive it goes and as long as the rpms stay up (^1500?)
it runs ok. Manually dropping it in 2nd and first as needed it makes it through town after town and I reach my harbor with just a couple frights. Just 90 miles to go.
I make it home again at speed no worries.
So now having gone through the Cold start temp/timing and the temp sensors
The CSI. The AFM, TPS, regapped the plugs, oh and the AV? (under the intake manifold) I'm ready to pull the ERG and test it.
As I wrote this I realize the low idle circuit is very suspect. But I don't know how that system is goverened/controled.
Any pointers or suggestions?

Co_94_PU

iTrader: (-1)

You are on the right path. Sounds like the EGT, hard starting requiring above natural (<1200) idle. I don't recall the speed the valve opens at exactly it is around 50-55 it throws the two trip code on the temp sensor models. Since you don't often reach the speed to enable the system the valve didn't like your sprint over the hill.

If you apply vacuum to the actuator you'll hear it slam shut when released, it'll also knock carbon loose that's jamming it. Or freeze it up solid and your no worse than you started.

Co_94_PU

iTrader: (-1)

Low idle is limited by the by pass chamber in the vafm, which generally speaking isn't adjustable or prone to failure. Low idle is adjusted with a similar bypass cast into the throttle body, the big flat screw.

The device under the intake is the high speed idle, actually cold air idle by pass thermo valve or something.

wyoming9

iTrader: (1)

It is the AAV auxiliary air valve

Coolant from the manifold heats the bi metal spring when the engine gets up to operating temperature the valve should be closed .

When at Air temperature the valve should be open

I have never seen one of these that still worked till The vehicle appeared .

After 20 plus yeas they tend to fail

I am curious how this plays out

osv

if it's going 35mph, it's not an idle speed situation.

long shot, i wonder if it's the engine harness corrosion problem.

Step Side 88

Spent the afternoon making another ( then another ) banjo bolt SST since I couldn't find the last one I made last year, but I have one ready now so will check the fuel delvery and pressure first thing since I think it acts like it's starving now. So I'll verify supply first.
the AAF is the one under the TPS correct?
I checked it out per the manual and it was ok.
as far as old crusty rubber goes this isn't.
it's still original but the truck was stored indoors every since it hit 56k which was when it was 'totaled' . Rubber and plug wires are all supple and stretchy. The only weak spots were right at a vac line nipple where it was removed by pulling instead of twisting first.

Thanks for the suggestions. I'll keep you posted.

Co_94_PU

iTrader: (-1)

You never gave results on the EGR valve. Does opening it have no adverse effect indicating it's already open and or leaking?

Step Side 88

Got sidetracked yesterday. Will try again today to run more tests.

Step Side 88

OK, after multiple software dumps I have a video of the engine running- or attempting to anyway.

NOTE:The Audio and Video tracks failed to sync properly so just close you eyes and use your ears...

First a shot of the fuel pressure taken with an old air pressure gauge so I question its accuracy but it at least shows something.

Then engine running on its own from turn of the key till dead followed by a cycle of it running with throttle 'assist'.


Next a shot of the plugs as pulled right after the previous two cycles.

Finally one more example of it on its own.
Only thing I have changed in all of the video was the idle adjusting screw.


As you can see testing the ERG isn't really possible as I understand things but then...
Its a mystery to me...

Co_94_PU

iTrader: (-1)

​​​​​You just need to apply vacuum to the EGR valve to make it open. If you don't have or want to procure a pump just pretend it's a thick milk shake.. Set the idle screw as low as you can get it to stay running then open the EGR, it should die. If it doesn't change at all the valve is stuck, and you need to take it off to find out if it's open or closed.

Now I'm going to go back and injest the rest of the post, like watch the video ...

Step Side 88

Thanks 94.
I can apply vac to the line so I will head out and see what that shows.
It IS the one component I haven't r&r'd wouldn't you know.

Co_94_PU

iTrader: (-1)

Can't see the plugs you'll need to post photos preferably medium to high res and more importantly in focus with good exposure. (You trigger focus and auto exposure by tapping the item on screen and wait for the green or red box, red means your to close or need more light green is GTG press the button to take the picture and try not to move)

One plug didn't match the others but it's hard to tell if that's video or something else. The last runs after around 4:30 is when I could finally hear the engine as anything but noise and it seems like a cylinder wasn't firing maybe at all.

Step Side 88

I'd like to isolate 'the problem' as much as I can.
Unless the miss fire or bad plug is causing the low idle issue I'd rather not go down another rabbit hole just yet.

As I said at the beginning, It ran fine 65mph up hill no problem. No missing or hesitation.
45mph no problem.
in town stop and go... no go.
the plugs vid was to show the plugs were all clean. No carbon or excess fuel.

Something governing low idle high idle, yet throws no codes is the hole I'm looking to diagnose first.

To my ear it sounds like it's starving for fuel. Is 18 psi that much to low and if thats the case why doesn't/didn't it starve on the freeway at WOT?

I have not pulled the injectors to test them but I see no reason to. It runs just fine once its going. It gets fuel.

Step Side 88

You mentioned the EGT in the beginning. How is it different from the ERG?

scope103

Exhaust Gas Recirculation. EGR. http://web.archive.org/web/200702040...77exhaustg.pdf All we all dyslexic here?

Co_94_PU

iTrader: (-1)

That was autocorrect should have been EGR.

Co_94_PU

iTrader: (-1)

If it's a plug, wire or something else really simple it's a quick check. Pull plug wires if it has no effect you might have found a dead cylinder. It is just to hard to hear the sublet differences in a video like this to determine over the internet if it's the same cylinder that coughs or multiple.
​​​​​​i diagnose the miss at higher RPM based on the plug wire #4 dancing about since the audio is just a roar with radio in he back ground..

Base timing, unlikely to have changed driving down the highway.
VAFM failure, unlikely to have broken the board in Just one place
TPS, unlikely while driving for the idle contact to wore out
Fuel filter, unlikely to be an intermittent clog symptoms are backwards


​​​​​​It likely is starving for fuel but it's sort of a red herring if it's shutting down the fuel pump due to the unsteady airflow caused by the poor idle.

Co_94_PU

iTrader: (-1)

Exhaust gas recirculation valve,

How did that test go? Obviously I was hoping for no change, since I didn't fully explain that if it stalled the engine it could still be leaking enough to cause problems at low volumes. To fully rule out leaks you'll have to block the port at the back of the intake.

Step Side 88

First the Air Valve per FAM sec. FI-66
RPM drops when hose is pinched.
second there is no ERG gas temp. sensor.

going into the EGR section of the Emission Control-12 in the FAM next since I just found it.

Step Side 88

OK here's a result.
Plugging ports P & R of the EGR vacuum modulator, air fails to pass through to the filter side from port Q...
So I'm thinking this is a positive..., No?
I mean at least its a failed test I can address.