CEL 71 - Where am I? (1 Viewer)

[BTLSHP]

We have had P0401 on and off for a couple of years. When I replaced all the hoses in May a removed the EGR, TB and Upper Intake I sort of ignored the FSM test procedure in favor of just doing things. Until last Friday, I felt like I had gotten away with one. But it is back.

In May:
Passages in the upper intake were thoroughly cleared of lots and lots of carbon.
VSV was tested - 30ohms on my analog and the solenoid fired with 12v applied.
All vacuum lines were replaced and the metal line through the manifold was clear.
As to the EGR Valve, I cleaned the pintle with B12 keeping the stuff away from the diaphragm.

Today: (I cracked the FSM)
1. The Vacuum Modulator appears fine.
4. There is no Vacuum at cold idle
5. b) I do not think I saw any vacuum @2500 rpm with a hot engine
5. c/d) I saw no vacuum @2,500 rpm with port R hose attached to a little metal vacuum port on top of the TB
7. a/b) Vacuum had no impact on idle quality when applied directly to EGR

Do I suspect a torn diaphragm in the EGR and replace? Or should I pull EGR for further tests?

Can I test VSV again from the connector end (and where is it). I would prefer not to pull IM again.

Anything else that I am missing?

 

[Malleus]

Why don't you just bring that truck to me and let me fix it? It'll save me a lot of typing.

 

[BTLSHP]

What is you favorite beer?

 

[Rifleman]

What is you favorite beer?

Even better then a beer, would be a nice single malt bottle of Glenlivet!

 

[BTLSHP]

Even better then a beer, would be a nice single malt bottle of Glenlivet!

I am easy it is near the end of the beer season for me anyway.

 

[Malleus]

Refresh my memory, this is a 1994, correct?

 

[BTLSHP]

Refresh my memory, this is a 1994, correct?

Yes, '94 with 235k miles. I was able to get an good ohm meter on the VSV wires at the connector for a resistance of 34 ohms and the solenoid clicks with 12v applied. I did not test for a short to ground.

 

[Malleus]

So, my approach to finding the problem would be as follows:

1) Conduct the MIL verification test (EG-229) and follow with circuit tests (EG-230).
Note: this procedure is ridiculously picky; you have to do it the way it's described. You'll have to do it again, after you correct the problem.
The purpose of this is to validate the self test capability of the ECM.
->assuming the results of Step 1) do not indicate a problem (fix whatever is wrong before continuing),

2) Perform the EGR system inspection (EG-185 to EG-186). These are the bullet points in the "Trouble area" column (EG-225):

[point 1, 2] Note: this set of steps (Step 7, EG-186) includes a check of the EGR valve (EGR Inspection, step 5: EG-190)

[point 3,4] Gas temperature sensor inspection (EG-214). Note: there is no inspection value for THG->E2 circuit. This circuit only passes current to the E2 terminal of the VAF (See EWD, ppg 57-58). So, if you have bad gas temperature sensor, or sensor circuit failure, it will affect the VAF operation.

[point 5,6] EGR system inspection, Steps 4, 5 (EG-185 to EG-186) are cursory inspections. You must also perform the VSV inspection (ppg EG-187 to EG-188) and Engine Coolant Temperature (ECT) Sensor tests (EG-300); the gas temperature and engine coolant circuits are simultaneous inputs to the VAF (both have to work - see EWD).
Note: you do not have to drain the engine coolant (but you do have to plug the hole - a fake cork from a wine bottle works very well; don't use a natural cork stopper).

->Be very careful removing the ECT harness connector housing (it's the green one, toward the front of the head) from the sensor; the sensors are readily available, but the harness connector housing is not. It is the only connector housing in the engine harness that is not available new (however, it is used on every '90s era Toyota engine, so you can get another from a salvage yard).
->assuming the results of Step 2) do not indicate a problem (fix whatever is wrong before continuing),

3) perform SFI ECU/ECM testing (Eg-232 to EG-251)
There isn't any way to know where to start without being there, so if you get here, you're flying solo.
-> complete system circuit diagram is on pg EG-206
->ECM values (service specifications (compete listing) (EG-332 to EG-324)

 

[Malleus]

If I was doing this, I'd print every page I listed (EWD in color), put them on a clipboard, and record the measured values on the pages where the steps are described.

I know that's not much in the way of real help, but it's all I got.

 

[BTLSHP]

Ok, This looks like my Friday adventure, though I might do the drive test tomorrow.

Clipboard sounds like a great idea.

3) OMG - that will be a challenge.

 

[Malleus]

Checking the ECM isn't hard, it's just tedious.

Good luck.

 

[BTLSHP]

Ok,

Ran the MIL verification test per EG-229 using my paper clip and after resetting the EFI fuse. A/C was off

Warmed up the car and drove 8 miles north on I-270 at a stately 60 mph. CEL light was flashing the entire time which I believe is correct for no codes and paper clip in place.

Got off stoped car and it would not restart -- tapped on starter motor and all is well. So another project for the list. Starter was replaced at 170k miles. I will figure out which on it is and order a plunger kit(?).

Back to the test, no steady CEL light during or after.

I plan to re-run this test after the engine cools.

 

[BTLSHP]

When the FSM calls for connecting to a vacuum source, I am thinking my little hand gauge is not what is referred to. I tried a couple of the little ports on the throttle body with no confidence there was steady vacuum. I tried the three small pipes in the lower left. Can I get stay vacuum elsewhere?

 

[Malleus]

Ok,

Ran the MIL verification test per EG-229 using my paper clip and after resetting the EFI fuse. A/C was off

Warmed up the car and drove 8 miles north on I-270 at a stately 60 mph. CEL light was flashing the entire time which I believe is correct for no codes and paper clip in place.

Got off stoped car and it would not restart -- tapped on starter motor and all is well. So another project for the list. Starter was replaced at 170k miles. I will figure out which on it is and order a plunger kit(?).

Back to the test, no steady CEL light during or after.

I plan to re-run this test after the engine cools.

Hot start failure is a symptom of a solenoid failure. I use the rebuild kits from ASPW. These are one of the exceptions to use of only OEM parts, since I've found their parts to be at least the quality of the OEM supplied to Toyota.

 

[Malleus]

When the FSM calls for connecting to a vacuum source, I am thinking my little hand gauge is not what is referred to. I tried a couple of the little ports on the throttle body with no confidence there was steady vacuum. I tried the three small pipes in the lower left. Can I get stay vacuum elsewhere?View attachment 3744105

You need a vacuum pump.

You can rent one for free at Advance and most other parts stores.

FWIW, it's a good idea to check the PERPARATION section at the beginning of each procedure. Any special tools required are listed there. The SST part numbers are for the dealerships. You don't need the Toyota approved tools, but you do need something that will do the job they were designed for.

 

[BTLSHP]

I have one of those. Ok!

Starter was replaced with a reman unit in 2015, 25k miles ago. The label on top is total unreadable - looks like red toyota label. I will look from underneath in an hour. Physically it looks like a Toyota casting....

 

[Malleus]

FWIW the starter Toyota used was also use on a dozen other non Toyota models, including Harley Davidson.

 

[BTLSHP]

Ok, ours was brought in through Southeast Toyota, so I am assuming there is a meaningful chance it had the 1.4kw originally. I will get under it shortly. I started on the front hubs last night only to discover the right outer bearing is pitted badly. Getting replacements from CruiserTeq tomorrow.

Also learned that someone has had a preference for using a chisel to manage the 54mm nuts in the past.

 

[Malleus]

You can get the bearings anywhere. They are not Toyota, or even Toyota specific, bearings.
Koyo LM102949/10
Koyo JLM104948/10

 

[Malleus]

Chisels are farmer's wrenches