Need 5.7 L TBI engine help - PLEASE - Tried everything

[hippiegroove]

I need some help if anyone may know whats going on.
I recently purchased an 89 GMC Van G2500 / vandura with the 5.7 l engine with TBI in it.
The owner stated her mechanic said it had collapsed lifters , which from my experience with Chevy / gm is very uncommon. I did notice some rust markings however like the motor had overheated pretty bad , so i tore into it.
Here is all i have done: I went and replaced the lifters , i replaced the timing chain , and i have replaced alot of the sensors. i replaced the Map sensor , the idle air control sensor , the throttle position sensor , temp sensor , and on the tbi the fuel regulator with gaskets and spring.
I also replaced the plastic vaccume lines with silicone lines , and the line under the frame that is metal and has a small portion being fuel line going to the emissions canister ( also replaced approx 1 ft by the canister as well before it goes to metal line ) I have played around with the timing on distributer and it seems to get a bit beter , but the vehicle stilll runs really sluggish.
i disconected the vacumme line from the Map sensor as well as the one going from the vacume sensor to the egr valve , and the Van seems to run and drive now - but still sluggish.
Prior to this it would start and idle , but would barely move when put in Drive and acted as if the TBI was flooding the engine with fuel before it could dump in the engine.
It also appears that there may be too much vaccume coming from the TBI ,and or manifold

any help on this would be greatly appreciated - Im to the point where all i can think of is that the ECU isnt responding properly , or perhaps the Injectors were replaced with higher fuel output vs the stock injectors..

I really dont want to throw more $ into this Van , and with all my GM experience have diagnosed as best as i can - Even shops cant figure this one out

[hippiegroove]

Also i changed out the Fuel filter on the frame - forgot to add that in my novel. in addition im driving the van with the dog house ofo , and as i accelerate i can hear what sounds like the timing chain clanking , or noise coming from the TBI as if there is way too much fuel dumping. in addition when i step on it , it looses power
Im just frustrated as all heck. Im good with most issues and trouble shooting, and this one has my brain working in overdrive
someone also mentioned something about a timing bypass wire , and i need to disconnect that when making adjustments..
Anyone know of this Timing wire , or is one of the 2 going to the distributer that plug in ?

[gmctrucks]

The timing wire is by the passenger side fire wall I think it's brown or purple someone else will confirm it. I'm wondering did you place the timing gears on correct also check your dizzy maybe it's seizing up also did you set the timing gears right it sounds so much like it's off. Why don't you set it to TDC and see if your rotor is pointing to the number one plug. I just woke up my brain isn't totally awake now and YES guys I do have one it's small but it's there. Beat you guys to it.
Good luck! GMC

[hippiegroove]

Originally Posted by gmctrucks

The timing wire is by the passenger side fire wall I think it's brown or purple someone else will confirm it. I'm wondering did you place the timing gears on correct also check your dizzy maybe it's seizing up also did you set the timing gears right it sounds so much like it's off. Why don't you set it to TDC and see if your rotor is pointing to the number one plug. I just woke up my brain isn't totally awake now and YES guys I do have one it's small but it's there. Beat you guys to it.
Good luck! GMC

I did set the timing to TDC on the harmonic balancer , and i made sure that it was at TDC compression stroke by pulling the # 1 plug. Also checked the dist , and it was pointing @ # 1. Also im told that with this motor it needs to be 0 degrees tdc and the computer will make all appropriate adjustments.
Also the cam and timing marks were right on - both pointing at each other where the dot is on both gears..

As for the timing wire - on a van is that accurate hat its on the passenger side firewall ? I was told my ecu was under the drivers seat - and to find out it was hidden behind the seat on the side of the van behind paneling.. so nothing is making much sense with this Van. I had to trace the wires to find it..

[Crmzendrgone]

As far as the location on a Van and the little known wire I couldn't tell you but like GMC said it would be brown for chevy I believe. and it goes to the distributor. It needs to be disconnected to set the timing at 0 and yes it needs to be at 0 with the wire disconnected.
I don't know why but the part you mentioned about

Originally Posted by hippiegroove

stepping on it and it loosing power.

makes me think plugged/clogged CAT.

Originally Posted by hippiegroove

i accelerate i can hear what sounds like the timing chain clanking , or noise coming from the TBI as if there is way too much fuel dumping.

That to me and me alone sounds like pinging so again my thought process is your running hotter that normal so the comp. is throwing more fuel in to help.(computer thinks you to lean) I dont know for sure I know there are some guys on here that are great with drivability. They'll join in(sshh I lite the batsignal)

[hippiegroove]

Originally Posted by Crmzendrgone

As far as the location on a Van and the little known wire I couldn't tell you but like GMC said it would be brown for chevy I believe. and it goes to the distributor. It needs to be disconnected to set the timing at 0 and yes it needs to be at 0 with the wire disconnected.
I don't know why but the part you mentioned about makes me think plugged/clogged CAT.

That to me and me alone sounds like pinging so again my thought process is your running hotter that normal so the comp. is throwing more fuel in to help.(computer thinks you to lean) I dont know for sure I know there are some guys on here that are great with drivability. They'll join in(sshh I lite the batsignal)

Prior to removing the vaccume hoses from the map sensor , and the vacume sensor - the van would idle and it at times would let me gun it to high rpm - but it seemed as if once the engine warmed up , it started bogging down and then it would quit running and take a while to start back up.
I know its not cooling related as i changed the temp sensor , flushed the radiator , put in a new thermostat , and the guage only goes a lil past 1/4 mark.
I also thought it may have been a clogged or plugged CAT , but i dropped the exhaust from the manifold and it ran the same way with all the vaccume lines connected.

I will try re adjusting the timing by disconecting the timing wire and see if that helps any , then clear it by disconnecting the battery and pushing on the brake to clear any trouble codes and post what happened after doing so. Probably sometime Sat morning when i wake up

[crabtruck]

Welcome to the forum hippiegroove.

"idle air control sensor "...."Injectors were replaced with higher fuel output vs the stock "

This is somewhat confusing as the IAC is a slave or "mod" but not a sensor or "decision maker".
..This valve changes postion on command of the ECM to allow more or less AIR.
..The injector "on" time is determined by various inputs to the ECM.
..By increasing the injector pulse, more fuel is delivered. IE: More pulsenot bigger Inj.

I'm thinking about all the work you've put in already, and two things come front.
1) Critical that you set the base timing with the proper wire disconnected.
..Believe that would be a Tan/Blk starting at 4-wire connector from Ign mod
..and has it's own disconnect somewhere before reaching ECM.
2) Let us know what codes you are dealing with, including whether before or after correct base timing set.

Note also that some bad ECMs 89-G-5.7 gave FALSE 32(EGR) and 45(RICH) codes.

FYI if unplugging IAC pigtail and ohming coils, they should be about 40-80ohms.

I have not heard about stepping on the brake to clear codes.
Removing the neg cable to do so works but is a bad idea because wipes fuel memory.
Preferred method would be with key OFF, remove EMB fuse for 1 min.
On some trucks disconnecting the in-line fuse holder near the Batt Pos,
or disconnecting the ECM power lead at the battery terminal works.

Is the emmission sticker gone ? Would have info on pulling timing wire and Timing Set.
Most likely 0TDC but some were 4BTDC .

[scavanger]

As said , disconnect the timing wire and set the timing, if you set it without disconnecting the wire timing would be off quite a ways. This alone might be your problem.
If you disconnected vacuum lines put them back on.
Do the following both cold and warmed engine for comparison.
Plugged cat. was mentioned. Find a manifold vacuum port connect a vacuum gauge. Start the engine, block the throttle at about 1500 to 2000 rpm. Watch the vacuum. If vacuum drops and engine slows, plugged exhaust.
You mentioned it looked as though engine had heated plugged cat would cause a lot of heat.

Scav.

[Chevy_Finatic79]

did you adjust the valves while the motor was running or just when you replaced the lifters not running? if the valves are too tight and never close it will run like **** and burn the valves also are you sure one of the cam lobes arent flattend out?

[hippiegroove]

Originally Posted by crabtruck

Welcome to the forum hippiegroove.

This is somewhat confusing as the IAC is a slave or "mod" but not a sensor or "decision maker".
..This valve changes postion on command of the ECM to allow more or less AIR.
..The injector "on" time is determined by various inputs to the ECM.
..By increasing the injector pulse, more fuel is delivered. IE: More pulsenot bigger Inj.

I'm thinking about all the work you've put in already, and two things come front.
1) Critical that you set the base timing with the proper wire disconnected.
..Believe that would be a Tan/Blk starting at 4-wire connector from Ign mod
..and has it's own disconnect somewhere before reaching ECM.
2) Let us know what codes you are dealing with, including whether before or after correct base timing set.

Note also that some bad ECMs 89-G-5.7 gave FALSE 32(EGR) and 45(RICH) codes.

FYI if unplugging IAC pigtail and ohming coils, they should be about 40-80ohms.

I have not heard about stepping on the brake to clear codes.
Removing the neg cable to do so works but is a bad idea because wipes fuel memory.
Preferred method would be with key OFF, remove EMB fuse for 1 min.
On some trucks disconnecting the in-line fuse holder near the Batt Pos,
or disconnecting the ECM power lead at the battery terminal works.

Is the emmission sticker gone ? Would have info on pulling timing wire and Timing Set.
Most likely 0TDC but some were 4BTDC .

It is 0tdc for the timing on the emission sticker. I am going to pull the plug for the timing set - # 1 plug again , make sure its at its compression stroke and at 0 on the harmonic balancer marking.

I will post what happens after i do this.

Im glad someone verified the ecm issues with running rich because thats definetly what its doing - and if the ecm can possibly be bad - what option would i have other than to replace it and hope it fixes the problem which is more $ that may or may not work..
Are there any aftermarket chips out there available to compensate the fuel ratio / egr so that it will run properly ?