High idle

[pappyam]

Hi
This is my first post. I bought a 97 Jimmy 4wd A/T 4 door with a burnt engine. I just changed the engine for one that I purchased from a 70 year old auto enthusiast that, purchased it new from a GM dealer 13 years ago. It was sitting on the engine stand all that time full of oil everywhere. He bought it for a project that never realized. We dismantled the heads and you could see that this thing did not have any mileage on it. Anyway, upon start up, the idle went right up to 3000+ rpm. After a few minutes, it settled down to 2500. I checked the throttle cable for binding but all OK. I disconnected the cable from the throttle body and idle went down to normal. I adjusted the cruise cable as per recommendations and now, idle is between 1000 and 1200 rpm. This is the same intake and fuel injection system that was on the other engine. Aside from the fact that the bad engine had a few spun crank bearings, it ran good. Nothing was changed besides new gaskets for the intake and the usual tune up items: fuel, air & oil filters and platinum plugs. Rotor, distributor cap and wires looked new and are AC Del co so decided to leave them on. All vacuum hoses seem fine and no vacuum leaks were detected. The MIL is flashing continuously after about 10 seconds that the truck is started. My code reader does not register any codes. I unplugged a few sensors to see if the pcm would register a code and it does so, I guess this means it is OK. I decided to take it out for a spin but, as soon as I put it in gear, it rattles and shakes from everywhere and eventually dies. I managed to drive it to access my back yard. It feels like it is working only on 5 cyl. I remember when I put the distributor back in, I could not get the rotor to align exactly with the #6 cast in the body but ,only a few degrees before it. My timing light shows 17 degrees advanced at 1000rpm and 20 deg @ 1200rpm. Is this normal or am I a tooth off on the distributor? Just for my sanity, could someone tell me which of the 2 marks on the damper is the tdc. Some say first, others the second while rotating in normal direction? I pulled a few wires while it was running and pulling #3 does not affect anything. I am not sure about #5. Seems like sometimes it affects the rpm's and sometimes it does not. Weird! Another thing. A friend gave me 2 O2 sensors that come from another, more recent 4.3 vehicle, of which I have no info. I had to cut the wires so I could refit my original O2 plugs. When I searched on line, I found that the Denso part # was not the same as what the 97 Jimmy would use. So I disconnected them. The tuck must stay in open loop cause the pcm still does not register a code. Too sum it up, high idle with no power and what seemingly looks like misfire and no DTC's. I know it is a lengthy first post but, I wanted to give the more info possible. Thanks for the help.
Don

[MT-2500]

The timing is not adjustable.
Computer controled.

http://files.automotiveforums.com/ga...hp?photo=51302

If you have a cylinder miss work on that end.

Always check egr valve plunger for stuck open or a carbon ball.

Does the missing cylinder/cylinders have good spark and good compression?
Dist cap and rotor and wires good.
Ac Delco cap and rotor.

How is the fuel pressure?

[pappyam]

Is this normal or am I a tooth off on the distributor?

Always check egr valve plunger for stuck open or a carbon ball.

This has been removed and cleaned as well as IAC valve.

Does the missing cylinder/cylinders have good spark and good compression?

Spark seems nil as I remove the wire. Compression should be OK as the engine is new. #3 cyl. is a pain to remove plug for compression check.

Dist cap and rotor and wires good.
Ac Delco cap and rotor.

Refer to original post.

How is the fuel pressure?

63 pounds with key on engine off and 55 pounds after about 3 minutes with key off.

All this has been going on for a period of 3 weeks since the engine has been installed. Right now, I am trying to diagnose what has been done and what is left to do as I had an eye operation yesterday and can not go out to work on the truck for a while. But if I have enough info to help, I will send a friend to do the footwork for me. Thanks
Don

[MT-2500]

The dist needs to be set as shown in picture.
And then camshaft retard setting checked on a scanner after start up.

If just One cylinder missing check spark and wire and cap and spark plug.
If OK better check compression.

[pappyam]

Before I have the #3 plug removed to check compression, I would like to know if dist. was off by 1 tooth, could this cause my MIL light to flash all the time?(Not on solid)
Don

[MT-2500]

Yes dist not set right can cause missfire.
Set it per picture I posted.
Flashing check engine light is cylinder miss firing.

[pappyam]

Thank you. Will try and have someone competent do that early this week.
Don

[viggy58]

get rid of the platinum plugs... these engines don't do well with them, especially when cold/first started. standard ac delcos well get the best performance.

also, the last time i had my dist off by a tooth it was similar. revved high until the comp could adjust, once it calmed down, the MIL would start blinking. Also, make sure the cap is seated well. pull it and check for any uneven burn.

[MT-2500]

Originally Posted by pappyam

Thank you. Will try and have someone competent do that early this week.
Don

When setting dist make sure it is on top dead center compression stroke.
To find the right TDC on ones with 2 timing marks always pull plug and feel top of pistion for true TDC and compression stroke.
Some rebuilt dist and replacement engines I have had to remove and turn dist gear 190 degrees.

Besides spark to plugs and compression and spark plugs.
Low fuel pressure and injector pulse and lean running engine can cause engine miss.
A steady miss on just one cylinder work on compression and spark and plug and injector.
Is the plug plug on the mising cylinder dry or wet on the end?
Make sure the injector plug in on top of engine is plugged in good.
And do not rule out a bad new plug or wire or cap.
You can switch plug and wire with another good cylinder to check that end.
On the fuel pressure check it with engine running.
You need 63-65 lbs engine running.

The only true test on a fuel pump is to check the direct fuel pressure from fuel pump.
A quick test is to block off the return line and see if fuel pressure comes up to 75-85 lbs.
But do not run the pump at full pressure very long.
Also when testing fuel pump and pressure you need to tape a gauge to outside windshield or outside mirror and drive it on the road for 20 -30 minutes
until the pump gets has run a while to check for a pump fading out after hot.

Hard to start cold or hot and fuel pressure testing guide lines.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
If pump has full pressure with return line blocked and low pressure without it blocked most usually the fuel pressure regulator is leaking or not holding pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak in system.
Post back fuel pressure readings.

[pappyam]

Thank you. I will post an update of what has been done so far shortly. In the meantime,the fact that the Mil is flashing steady , the O2 sensors unplugged and no codes stored got me thinking and curious. After checking under the hood, the emission label states "Conforms to the Canadian emission act" and does not show anywhere that it is obdll compliant. My Inova 3100 code reader does not read any codes although if I disconnect certain sensors, it will register a code. I just got my ElmScan 5 today and tried it. Here are the results. I asked on another forum and was told that 96+ are compliant. But in Canada, I beleive it was mandatory starting in 98. In any event, my scan tool's freeze frame data is not available. Could this have anything to do with the DLC? BTW, I called 3 GM dealers and no one could give me a definite answer short of putting it on the Tech2. The truck is in the yard with no plates on therefore, I can't go on the road to test it. At $325.00 for plates over here, I don't want to plate it and let it sit any longer than needed. If anyone needs the VIN to check, here it is: 1GKDT13W0V2565346 Thank's
Don

[viggy58]

anybody think the ECU might be shot? I would assume, that even though it's canadian, it would still have been fitted with an OBDII system in 97.

when you bought the engine, did it come with an ecu? if not, yours may need to be re-programmed for it.

[pappyam]

No, it did not come with an ECU. But seeing that all the emission components except the crank sensor are original to the previous motor, I don't see why it would need reprogramming. I removed the I/P sound insulator so I could get a look at the DLC.All the pins that are part of the obdll standard are populated. I managed to find a diagram of the connector and will be probing the #2 serial data signal wire for either a short or open today.
Don

[pappyam]

Well, I tested the #4, 5 ground points and #2 serial data link for open or shorts. Everything seems fine. Tried different scan tools (borowed from frends) and same thing. They either state not compliant or does not conform to any standard and I can read some, but not many pid's. I wonder if the fact that my O2 sensors are not plugged could have an impact on this. Will try again tomorow and if it is still the same, will try to find support on the GM website to get an answer. And also, I did try the scan tools and decoders on other cars and they work perfectly.
Don

[82Stang]

Just for the sake of saying not sure if it pertains to your problem but, my 93 Blazer started and idled very high and I had no code for that. it turned out to be two things. An IAC valve, which I had already previously cleaned but didn't do the trick. A junkyard one, DID do the trick. And a new intake plenim gasket, which I'm sure you already did. I'd recheck the IAC and other things like the EGR, and MAP sensors. They reek havoc with the idle.

[pappyam]

Yes I did replace the gaskets. I might have found something but I don't know how to decypher this. Can someone help?
Don