Chevy 350 Another Puzzle to Solve?

[acoen]

Ok....First I want to thank everyone for helping me chase down the leaking intake manifold gasket. That was a weird thing....
Now I have another issue that is driving me crazy, mostly because trying to find specific information on the net for a Chevy is nearly impossible (so much information you can't pinpoint specifics) I can't find the information I need for this damn 1989 Chevy 350 4x4. (ie, IAC counts, TPS voltage, test proceedures for various sensors, troubleshooting tree). If this was a Toyota or GN/TR I would have found it easily.

I timed the engine, adjusted IAC and TPS, changed the EGR, fuel pump relay, FPR and O2 Sensor. The problem: The truck barely runs in open loop, gray smoke, studdering and lopping. When it hits closed loop it starts and runs better. Once it is on the road it acts as if it wants to die. Then straighten's out then starts to want to die and sputter all over again. At first I thought it was the FPR, running rich and lousy....Changed that with no change in problem. Then I received a code 44 and 32 one is EGR and the other is an O2 lean condition, so I thought wow it is running like the EGR is cracked open, the EGR seemed stick and bind so I replaced the EGR and O2...Did this today with no results, thing runs horrible in open loop better in closed loop. I checked my timing, IAC and TPS, ran a vacuum test to see if I had vacuum leaks and I have 24-25hg in vac. Timing is dead on, I also tried unplugging the sensors one by one....coolant temp, O2, IAC..etc to see if one was causing trouble. I also readjusted my TPS and IAC, again!

Fuel pressure is my last test to perform, but not sure how to do it on a TBI system? I do get fuel and a bunch of it when I crank the engine over. The injectors seem to spit and sputter when it is in open loop. A ton of fuel once in closed loop. Once it warms up, I have an idle around 1500 RPM, (why I do not know)... I've looked at a couple of sites and seen that others have had the same exact problem, but nobody seems to reply with the cure.....Any help....What am I missing (pick up coil, fuel pump, egr switch, TPS, Map sensor, ECM)? Tough to find specific information on these chevys. If I had a good troubleshooting tree and specs on testing sensors I could rule out a ton of stuff. Troubleshooting an 86-87 TR is easy compared to this freaking thing.

Seems to have gotten worse by changing the EGR and O2, seems like I improve one thing and the system gets all out of whack. The factory idle setting and TPS were way off, but I set the TPS to .5v and the IAC at 700 RPM per specifications (no counts could be found on the net)....Help Please before I torch this damn thing

Thanks guys, sorry for being a pill.

Aaron

 

[chopped39]

Did you check distributor? pole piece cracks and will cause all kinds of problems. One more question. is this the stock engine or has it been changed? I have seen reman engines come with wrong timing covers.some have mark towards the left side of engine and some are under waterpump. good luck

 

[acoen]

Did you check distributor? pole piece cracks and will cause all kinds of problems. One more question. is this the stock engine or has it been changed? I have seen reman engines come with wrong timing covers.some have mark towards the left side of engine and some are under waterpump. good luck

WoW! Thank you for the quick response....

I believe it is the stock engine. What part of the distributor is the pole....The shaft?

Thank you....I will check once I know what part of the distributor that is....Thansk again

Aaron

 

[meanchicken]

I had similar sounding issue on my ZZ502 (carb'd engine)...ended up that the center contact on the rotor was not making good contact with the dizzy cap. We tweaked it up a bit so it would make better contact....problem solved.

Have you checked to see if all your cylinders are getting good spark?
Coil and spark plug wires seated good?

Cracked towers (poles) also can be a problem. Look inside the cap. If you see carbon traces between poles (the metal pieces that go up into the towers) you might have a dirty or cracked dizzy cap.

 

[chopped39]

WoW! Thank you for the quick response....

I believe it is the stock engine. What part of the distributor is the pole....The shaft?

Thank you....I will check once I know what part of the distributor that is....Thansk again

Aaron

When you pull off rotor you will see the star looking thing under it, Look real close at it and look for small cracks .I would also check cap and rotor.

 

[acoen]

I had similar sounding issue on my ZZ502 (carb'd engine)...ended up that the center contact on the rotor was not making good contact with the dizzy cap. We tweaked it up a bit so it would make better contact....problem solved.

Have you checked to see if all your cylinders are getting good spark?
Coil and spark plug wires seated good?

Cracked towers (poles) also can be a problem. Look inside the cap. If you see carbon traces between poles (the metal pieces that go up into the towers) you might have a dirty or cracked dizzy cap.

Dizzy cap is the rotor? Sorry I'm hearing some new terms. I've been buried in the engine bay of TRs for too long:wink: Good place to start, I thought distributor since it has been out. Timing is right on and I'm not a tooth off. But I will check the cap and rotor for cracks.

 

[acoen]

When you pull off rotor you will see the star looking thing under it, Look real close at it and look for small cracks .I would also check cap and rotor.

Very good points, I was just telling my wife that I should have checked that first. would make since 157k miles on the engine with recent valve job. I have noticed that there is some green brittle buildup on the contacts inside the rotor. It was strung between contacts in the direction the rotor spins...We may be on to something here.....Maybe Coil? ignition module inside the distributor (not sure if it has one).

 

[Phoneguy]

Aaron, give me the model of what you are working on. Pickup/Blazer. My neighbor is a sales rep for All Data, I will see if I can hook you up with what you need.
Bryan

 

[chopped39]

Very good points, I was just telling my wife that I should have checked that first. would make since 157k miles on the engine with recent valve job. I have noticed that there is some green brittle buildup on the contacts inside the rotor. It was strung between contacts in the direction the rotor spins...We may be on to something here.....Maybe Coil? ignition module inside the distributor (not sure if it has one).

If you are in good with a parts store near you? I would see if thay have a reman dist in stock. drop it in and see what happens.

 

[acoen]

Aaron, give me the model of what you are working on. Pickup/Blazer. My neighbor is a sales rep for All Data, I will see if I can hook you up with what you need.
Bryan

Sure thing.....1989 Chevrolet C1500 4x4 350 (I believe engine series Z)

Thanks my friend.

Guys it has to be simple, has to be! The cap and rotor thing sounds really good. The green streaking in the cap is almost a giveaway.

 

[acoen]

If you are in good with a parts store near you? I would see if thay have a reman dist in stock. drop it in and see what happens.

That may be a good idea....I like your's and meanchicken's idea about checking the cap and rotor....Sometimes things can be that simple, we will see. Thanks again.

 

[T Rubble]

this sounds like the same problem my buddy has on his 1991 camaro 305 tbi. Let me know if you figure this out because we have replaced everything on his car and it is still not running right.

 

[Phoneguy]

Sure thing.....1989 Chevrolet C1500 4x4 350 (I believe engine series Z)

Thanks my friend.

Guys it has to be simple, has to be! The cap and rotor thing sounds really good. The green streaking in the cap is almost a giveaway.

You are welcome,
Give me a couple days and I will see what I can do.
Bryan

 

[Junior Samples]

Arron,

1. on the high side the Ohm meter should read infinity
2. on the low side it should read low or zero
3. on high side it should NOT read infinity

Coil wire resistance 1,000 per inch.
Pick up coil resistance should be between 500 to 1,500 ohms, flex harness and observe resistance, if it fluctuates then pick up coil harness is damaged.


Dumb Que but you changed fuel filter correct?
Also could very well be cracked distributor cap, rotor etc
TBI you have to install your own T-fitting to hook up fuel pressure tester
ive always found that when ignition module was getting ready to die it acted like it was running out of fuel then just up and died.

 

[acoen]

Arron,

1. on the high side the Ohm meter should read infinity
2. on the low side it should read low or zero
3. on high side it should NOT read infinity

Coil wire resistance 1,000 per inch.
Pick up coil resistance should be between 500 to 1,500 ohms, flex harness and observe resistance, if it fluctuates then pick up coil harness is damaged.


Dumb Que but you changed fuel filter correct?
Also could very well be cracked distributor cap, rotor etc
TBI you have to install your own T-fitting to hook up fuel pressure tester
ive always found that when ignition module was getting ready to die it acted like it was running out of fuel then just up and died.

I will check the coil...Yes I checked the fuel filter, wasn't plugged at all. The problem reminds me when a Mass air flow sensor is going out. Weird thing is fast smooth idle, that is when I adjusted the IAC and TPS. I would notice from time to time a stumble, driving down the road like a hiccup, then it would run fine. Also it hardly runs in open loop, then closed loop it will run much better, high idle, gray smoke on accelleration with hiccup and studdering. I did notice the inside of the cap being discolored at the posts, green crusty stuff....sure sounds ignition related, maybe ignition module?

I've been thinking maybe I'm a tooth off, but it times too good and runs good when it runs just getting progressively worse with every bad part I change, ie FP Relay, EGR and 02 sensor.

 

[acoen]

I just wanted to say this is one of the best sites around...I am confident I will solve the problem with the help from all you....thanks again.

 

[Junior Samples]

Arron,

I took a little better look at post but im

Ok it starts up and has nice smooth fast idle but yet in openloop it runs like crap But then in closed loop it runs much better?

i thought about it at work this morning and its like if you start up and it runs good then in closed loop it runs like crap that would tell me the ecm? or an ignition issue...like cracked coil or module going bad lets say..cold it runs fine but as it heats up it poops.
its like the total opp... you might pull out your IAC and clean it?... on first start you should hear it adjust via rpm
You double checked for vac leaks and all your symptoms also point to fuel delivery but your not there yet

man i dont know, maybe Chuck L can make heads or tails of this...Chuck help!

 

[acoen]

I think I confused some folks, hell I confuse myself sometimes....Basically runs horrible when cold she will hardly run....cough, sputter, choke, die. Crank sputter, choke, gasp die. All while fluttering the pedal. When closed loop is reached or warm, she will fire up and run somewhat smooth, but will surge and buck from time to time while driving and have a high idle speed and gray smoke.

Here is what I have found
1. Runs horribly in open loop, choke, gasp and sputter, have to flutter the gas pedal to keep it running long enough to reach closed loop (warm)

2. Closed loop or warm runs better but high idle, surge and buck while driving.

3. Found green crusty deposits on the posts in the distributor cap...quite a bit, crunch crusty stuff. Weird?. (cleaned and replaced cap)

4. Replaced FPR no change

5. Replaced FP relay

6. drove it and coded 44 and 32 (I believe or 34 one of the two that is for 02 sensor lean condition) EGR and 02, may have caused these by moving the EGR valve prior to start and unplugging the 02 while running.

7. Replaced 02 and EGR valve (valve was sticky and rough)....No change

8. Checked and adjusted timing to factory specs, 0 degrees BTD with the wire disconnected.

9. Adjusted TPS to .5 volts idle and IAC jumped A and B to elongate pintle, unplugged the IAC adjusted idle to 700+/- RPMs idled well. ECM voltage to TPS 5 volts.

10. Vacuum gauge test 25hg vacuum steady.

11. test for fuel, unplugged one fuel line and cranked the truck over....a ton of fuel in a very short time while cranking.

12. Unplugged sensors one at a time to see if there was a change...nothing from coolant temp switch, O2 switch, IAC motor, EGR switch...

13. Poured water along the intake no change.

13. drove last night worse bucking and surging in closed loop. Gray smoke

Remindes me of when a MAF goes out or is going out of whack.
My guess is distributor related...seems like everytime I mess with it things get worse. What mode is the ECM in while in open loop....grounding problem? Distributor need to be grounded I have a gasket between the distributor and intake. Wonder if I have a bad ECM ground...I may be on to something here. gasket on intake coated on both sides with RTV, every bolt coated with RTV. Two grounds for injectors and sensors connected to intake....Maybe? But there are other things bolted to intake like power steering pump brace, idler pulley brace, AC brace.....HMMMM? Any thoughts

 

[Junior Samples]

well dont feel bad, i was out in garage, removed my maf pipe and just for the heck of it i checked my side to side play on my compressor wheel and holy SSSS$$$$$hhit, yep thats right and only about 140 miles on brand spankin new ta-49 so i called precsion and he for sure wants to see, I got center housing in box ready to ship

It may be your module if it feels like its running out of fuel but you also need to test your fuel pressure..starting to sound like ignition though

 

[acoen]

well dont feel bad, i was out in garage, removed my maf pipe and just for the heck of it i checked my side to side play on my compressor wheel and holy SSSS$$$$$hhit, yep thats right and only about 140 miles on brand spankin new ta-49 so i called precsion and he for sure wants to see, I got center housing in box ready to ship

It may be your module if it feels like its running out of fuel but you also need to test your fuel pressure..starting to sound like ignition though

I may see if my buddy is working at Kragens and pick one up just to see if that is not it take it back

BTW....Gotta love that K series Blazer (I think they were K series)

Here is me and my long gone WE4...miss that car...Hemmings Motor News: 1987 Buick Regal Turbo-T

Look hijacking my own thread