Engine won't idle with Spout installed

2trux · Jan 28, 2015

Engine won't idle with Spout installed **Solved**

Hey all,I am having an odd problem with getting my rebuilt engine running correctly. After installing my engine I got it running and timed with the Spout plug out. It seemed to be idling OK at that point. After replacing the Spout the truck would not start. Take it back out and it starts up.

Things I have observed:
When idling the RPM fluctuates 800-1100 RPM
Seems to have an intermittent miss
Unplugging the IAC at idle kills engine.
Unplugging vacuum to MAP kills engine.
Unplugging air temp sensor in manifold kills engine.

I can plug in the Spout when the engine is running at 2000 RPM and I can see the timing advance, so that seems to be doing what I expect.

Thoughts in my head:
Valves not adjusted correctly. (Set to 1/2 turn, adjusted on stand)
Injectors not working correctly. (Cleaned, micro filter & o-rings replaced)
Spark plugs. (New less than 1000 miles ago)
Vacuum leak. (All new gaskets during rebuild)
???

I will buy a vacuum gauge & compression gauge tonight to see if there is any odd readings.

Is there any way to test the injectors? Pull the rail and turn key on and check for leaking? Crank engine and check for spray? (Is this even possible?)

Any other ideas for things to check?

Thanks

RonD · Jan 28, 2015

You can pull the coil wire(no spark) and crank engine, then check spark plug tip for fuel.

SPOUT wire connects TFI to Computer, this is for signal coming from computer to TFI module, by unplugging it you remove the computers ability to change spark timing.

PIP wire from TFI goes to the Computer as well, this signal is from the sensor in distributor and goes to the computer which allows computer to set injector timing, then control spark advance and retard based on other sensor data via the SPOUT wire.

TFI module has a separate START and RUN circuit.
When starting engine SPOUT is basically disconnected so TFI module is running spark timing directly, and computer times injectors with PIP signal.
START wire on TFI module is connected to Starter relays "S" wire so when key is in START position TFI's START wire and the relay should both have 12volts present, when key is released(goes to RUN), the 12v is gone, TFI then looks to SPOUT for timing signal.
You can remove the "S" wire at the relay so starter motor won't crank, and then test for 12v at the TFI module when key is turn to START, test light is good for that if you don't have a helper.

You comment about the no start with SPOUT connected but starting without SPOUT connected would lean me towards an issue with TFI module and START wiring.

Good read here on checking the TFI wiring: http://www.therangerstation.com/tech_library/TFI_Diagnostic.shtml

kimcrwbr1 · Jan 28, 2015

Have you checked for true TDC yet. If the damper pully is old it could be not reading correct. Use a piston stop tool to check for true TDC. Pull the #1 spark plug and turn the crank so it is at TDC on the timing marks then turn the crank about 30 degrees. Install the piston stop tool and touch the piston and mark the damper pully at the pointer then turn the crank by hand one revolution until the piston hits the stop tool and mark the damper again. Measure the distance between the two marks on the damper and that is true TDC. Disconnect the batter when you install the piston stop so you dont accidentally drive it through the piston with the starter. One you confirm TDC then set the base timing exactly at 10 degrees BTDC with the spout removed. If you disconnect a senser while the engine is running the computer will go into limp mode and best to just disconnect the battery for ten minutes and then run it for another 20 minutes so the computer can set new values. After running 20 minutes then you can pull the codes if necessary?

kimcrwbr1 · Jan 28, 2015

http://www.youtube.com/watch?v=RENhHI9n65I
A quick tutorial

2trux · Jan 29, 2015

Thanks for the ideas. I just had a short time available to do some work on the truck last night.

I blocked the IAC and used the idle screw to set idle. This got rid of the fluctuating idle. I ordered a new IAC.

I retarded the timing and got the engine to run with the Spout installed. It is still missing & I think this is why it won't idle when the advance is high.

The damper slipping seems unlikely since it timed fine before I pulled the engine to rebuild it, but I will check it.

Plan for this weekend:
Verify TDC to mark on damper.
Redo rocker/valve adjustment.
Test fuel injectors.
Check compression.

Any other things I should look for or test?

Thanks

kimcrwbr1 · Jan 29, 2015

I remember a while back on reading how to adjust the antidiesel screw. Open the throttle to around 2000 rpms and the IAC should be fully closed and disconnect the IAC then set the idle stop or in this case antidiesel screw to 650 rpms. Then plug the IAC back in and it should control engine idle. When you let off the throttle quickly it allows air into the manifold until the IAC takes control. Disconnect the battery for at least 20 minutes after confirming base timing at 10 dbtdc. Check all senser are connected and connectors are clean and put together with dielectric grease. All vacuum hoses are soft and tight on the ends. Start it and run it for around 20 minutes at medium speeds so the computer can set all the new values. Sometimes it takes a couple complete warm up cycles for the computer to dial everything in. Take it for a short road trip and if necessary then you can pull the codes while the engine is still hot.

kimcrwbr1 · Jan 29, 2015

Any time you change, clean or unplug a senser while the engine is running you need to reset the computer by disconnecting the battery for 20 minutes. Then give it a little time for the computer to set the new values.

kimcrwbr1 · Jan 29, 2015

You did put a new PCV valve in correct?

softshellcrab · Jan 29, 2015

I had the exact opposite problem. With the Spout out, it ran like a dog: the timing was retarded. Spout back in and it runs like a raped ape.

kimcrwbr1 · Jan 29, 2015

softshellcrab said:
I had the exact opposite problem. With the Spout out, it ran like a dog: the timing was retarded. Spout back in and it runs like a raped ape.

That is why he needs to confirm the base timing you cannot do it by ear you have to set it with a good timing light. 10 degrees no more no less.

2trux · Jan 30, 2015

kimcrwbr1 said:
I remember a while back on reading how to adjust the antidiesel screw. Open the throttle to around 2000 rpms and the IAC should be fully closed and disconnect the IAC then set the idle stop or in this case antidiesel screw to 650 rpms. Then plug the IAC back in and it should control engine idle. When you let off the throttle quickly it allows air into the manifold until the IAC takes control. Disconnect the battery for at least 20 minutes after confirming base timing at 10 dbtdc. Check all senser are connected and connectors are clean and put together with dielectric grease. All vacuum hoses are soft and tight on the ends. Start it and run it for around 20 minutes at medium speeds so the computer can set all the new values. Sometimes it takes a couple complete warm up cycles for the computer to dial everything in. Take it for a short road trip and if necessary then you can pull the codes while the engine is still hot.

That's good info, thanks.
I did not disconnect the battery after setting the base timing. I will go back and repeat this.
The problem with setting the idle stop screw is my IAC never closes, so this will have to wait until the new one arrives.

kimcrwbr1 said:
You did put a new PCV valve in correct?

I replaced it less than 1000mi ago when I bought the truck.

2trux · Feb 2, 2015

*Solved*

Odd as this may sound, the problem turned out to be the distributer in the wrong position. When #1 was TDC the rotor was halfway between 1&4. I moved the dist to be back on #1, timed it and it runs great.
I'm not sure how it ran the way it was and still show correct timing.

As a side note I did learn how to check my injectors to see if they worked. Turns out they all spray just fine. They just shoot out a single stream, so I am hoping the new 4 nozzle Bosch injectors I bought will atomize the fuel better.

Thanks for all the input.

ab_slack · Feb 2, 2015

I was wondering myself if distributor position was the issue (easy to sound smart after the fact). lol

Going back to Ron D said about the pip signal I was thinking if that was wrong position either the signal was wrong or out of acceptable bounds. Since it worked with SPOUT out, it wasn't relying on that pip signal at all.

Engine won't idle with Spout installed

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