88 1/2, 5.7L Engine stalls?

[bearcat58]

Ok, I think I have done just about all I know what to do.

Vehicle = 1988 1/2 k1500 shortbed, with a 5.7L TBI, Automatic with OD. It has about 300,000 miles on it but the engine and trans were replaced about two years ago. I LOVE this truck.

Problem= One morning last week it would not start. No Fire at all. I looked into the TBI and it was getting fuel. Pulled a plug- no fire. I then pulled the coil wire and (holy #$%^- ), yes it did have fire. I then replaced the distributor cap, rotor, Plugs (gapped to .040), and plug wires. Still no fire at the plugs. I pulled the ignition module in the distributor and had it tested at AutoZone. out of the four tests, it failed 3 times. I replaced the module and the pickup coil in the distributor. I even replace the main ignition coil just to be safe. Now it started very fine......all until it goes from open loop to closed loop control. It Idles and revs fine until after it warms up....if I put it into gear, it dies. It will stay lit if I power break it. I have check the timing with the (tan/black strip) wire disconnected. Is exacly at 0 degrees. I then replace the ESC module, the TPS sensor, the PCV valve, and the TBI lower gasket. The TPS sensor is reading 0.5V at no throttle. I hear a clicking at the IAC valve.
I still am getting a code-42 from the ECM.

Anyone have a suggestion?
Thanks- Bearcat!

[Autopro1962]

Sounds like you replaced alot of parts you can try this.
1. Verify the Electronic Control Module (ECM) has good powers and grounds.

2. If the engine runs better with added carburetor spray, check for 10-14 PSI with the engine running.

3. Check for a stuck open Exhaust Gas Recirculation (EGR) valve.

4. Verify the Idle Air Control (IAC) motor retracts for a fast idle start up flair with the Key On Engine Off (KOEO).

5. If the engine stays running with the set timing connector disconnected, check for a weak distributor pick up coil output.

6. Disconnect the distributor pick up coil connector from the ignition module.

7. Verify the AC voltage output from the pick up coil is over 700 mV at a FAST cranking speed.

8. If not, replace the pick up coil and install a NEW distributor shaft

[Autopro1962]

If you don't want to go threw all that just replace the dist. shaft it's a common problem.If you didn't already have all them knew parts in the dist.I would say just pick up a rebuilt dist.and drop it in.

[bearcat58]

Ok, I thought we had this one nailed! I disconnected the EGR valve and plugged the hose line, started it and let it warm up. It went through all the gears ok, so I took it for spin. Seemed to run ok for a while. Got it up to 50mph on the outer roads. When I came to a stop, it would Idle as normal for a moment (30-45sec) then the it would Idle down, shutter and stall. It started up just fine. Sounds like it also has a miss.
Also, it seem that it takes a long time to rev down after sharp accel. Not the same power it had also.

[bearcat58]

I have almost changed out all that is available to change.
I just change the IAC in the TBI. It is running better (more power) but it still stalles after long idle or put into gear in idle.
I rechecked my code= 43 now.
Please help anyone?

I'm thinking I might change the fuel pump now. I have heard it is easier to move the bed back to get to the tank. Has anyone done this befor?

[Autopro1962]

I would suggest that you make sure the dist. shaft is working right,did you check the voltage output?The shaft has a magnetic wheel and it weakens over time,also the bushings get worn.Does it stay running with the timing wire unhooked.Sure would be alot easier if you could test the fuel pressure with a gauge before you go to all the work of replacing the pump,if you test the pump psi 10-14 running and with the return line pinched of (deadhead)pressure min.of 17psi.With out a hoist some people do think it is easier to move the box.Goodluck

[bearcat58]

The pick-up coil in the distributor is one of the first things i changed. Took me for ever to realign the oil pump.
I will research on how to check the voltage output on this and make sure this is not a concern.
I have read that a code-43 points to the knock sensor and the ECM might be trying to retard or advance the timing incorrectly. Problem is....I have already change this sensor too. By the way...is there supposed to be antifreeze behinde this sensor?

[Autopro1962]

The knock sensor screws into a water jacket so that is normal.If you unplug the wire from the pickup coil that gos to the module (two wire plug)take your volt meter and hook it to the plug from the pickup coil then crank over the moter and you should have over 700 mv.The pickup coil is powered by the magnetic star wheel on the dist.shaft and when the magnets get weak on the star wheel that is where you get the problem.The magnetic pickup coil produces its own voltage as long as the star wheel on the shaft isn't weak.
I have replaced 100 of them over the years most of the time I will just get a rebuilt dist because it comes with a new module and pickup coil in it.Sometimes the star wheel even gets a little lose on the shaft.So your pickup coil that you replace is find its the shaft that is giving you the headache!If you have to take the dist out again I'm sure you now to get it back how it was.When I have a problem with the pump shaft most of the time it falls right in in the wrong spot so I just lift it back with one hand on the rotor just anuff that you can move the rotor,move it one tooth at a time dropping it back in each time and walk it around to the spot you need.Hope this helps.Hard to believe nobody else has responed to your post!

[bearcat58]

So am I to infer- There is a permanent magnet that drives this disributor pick-up coil that might get weak? Makes sence. I remember replacing a distributor shaft on another truck......It would jump to position when I rotated it via the rotor. This one does not. I will do what you suggest........and let you know how it turns out.
Thanks for the response.
Bearcat!

[Autopro1962]

You are right it should jump to the the points on the star wheel on the dist. shaft if not the magnets are weak.

[bearcat58]

Ok, I've replace the distributor with a "New" one. It now runs a lot better and does not stall when put into gear at idle......even when warmed up. Now, on heavy acceleration a speeds above 40mph, the check engine light comes on. It still comes back with a code-43. I have replace the knock sensor. I do not know where to go from here. Is it possible that there is just enough of a knock to confuse the ECM?

[Autopro1962]

Here is a couple things on that code 43
1. Access the knock sensor module located to the right of the throttle body. Disconnect the module and connect a voltmeter to the blue wire at terminal E going to the knock sensor. Tap on the exhaust manifold and check for the knock sensor to produce its own small amount of voltage (tenths of a volt). If not the wire is bad.

2. Verify the module has power on the Pink/Black at terminal B and ground at terminal D on the Black.

3. If OK, check the Black wire at terminal C for approximately 9 volts coming from the Engine Control Module (ECM). If OK, ground the wire and check for a knock signal indicated on the scan tool. After engine installation, it is setting code 43 on a hard acceleration-With the engine idling in the stall, and code is not a current code, tap on the engine block. While tapping on the engine with a hammer, check the scan tool to see if a knock is indicated? If a knock is indicated, then because this is a fresh engine, it does not have the ability to ping. Advance the ignition timing by 6 to 8 degrees before Top Dead Center (TDC).Also with alot of these I have seen that it has a bad curcuit in the ecm and alot of people just live with it bacause the truck is running ok but that is up to you.

[bearcat58]

OK....thanks. I will do all of the voltage tests although I do not have a scan tool. I tried to download on of the software packets and purchase a connector cable. When I downloaded and installed the "TunePro" program...........it took over my modem completely and would not give it back. I had to formate my hard drive and reload W-XP.

By the way..............................You say to bang on the muffler?

My exhaust system is almost shot............I know it rattles quite a bit.
Could this be doing this?
I have plans to replace the intire system including the Cat soon.

[Autopro1962]

Not the muffler,the exhaust manifold,just kinda tap on it with a small hammer,like on the same side by the knock sensor I use a long 3/8 extention to tap.

[Autopro1962]

Normaly that code sets if the ECM is not detecting a knock,so your muffler making noise would not set the code.So most likly open wire,bad connection,knock sensor module or something with the ECM or the engine just isn't producing a knock thats why one of the things to try is bump up the timing.