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At wits end!


PeteyPathy
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Here it goes. I'm desperate for advice guys. 87 2door 4x4 309k!on way to work couple weeks ago stopped at c-store truck ran great. Came out of store truck cranked and died. So what the hell its never done this before? Cranked it and feathered throttle got RPMs worked up (thank god she's a stick shift) limped her to work. It has had a CPS code since I bought it.

 

 

 

Pulled codes showing different CPS code and TPS code, tested coil it tested bad, while changing coil found resin on back of ICM melted, that's never good. Replaced TPS ICM and CPS as well as coil. Fired her up started good, died. Can feather throttle and get reved up, once up about about 3k it runs pretty good but no power. So i went to checking vacuum lines found 1 that wasn't secured and had gotten against belt replaced this, otherwise looks like PO had replaced all vac line they are in very good condition. Pulled and checked EGR didn't look so good so i made blocker plate to stop egr flow in case it really was stuck open. When i get it running was putting out very strong gas smell now smells very lean. In process of installing CPS found 2 plug wires that distributor end was almost corroded off, replaced the 3 plug wires on that side and gapped plugs. I had already replaced 3 on other side previously because they were taped together by PO, just hadn't gotten around to doing driverside. I also sprayed through MAF air passage with electric contact cleaner. I noticed that only 1 injector is firing, after a rigged up a way to keep it running while i was under the hood, is this normal?

 

Any help you guys can lend will be greatly appreciated!

 

Peter

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Check the grounds. Almost all of the engine sensors share a common ground. Poor connection and many things can go gunnywaggle on you.

 

We've also been having a slough of injectors going bad on the TBI engines lately.

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Can you give me a rough idea where grounds are supposed to be located? I'll definitely check that. At this point if someone said put 2 aspirin and a cup of coffee in fuel tank i just might try it lmao

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Cleaned all grounds, no change, checked ECU connection and MAF both look good. Found one blick ground disconnected, made new ground to replace it.

 

Update i have now isolated it to a vacuum leak, but seems to be either a solenoid or actuator. With vac gauge on it i can rev way up and slowly back off shows no vac and runs like a$$ till suddenly whistling dies down, vac comes up, if I hold throttle steady at that point (usually around 2500 rpm) then as smooths out rpms come up about 1k and runs right for 10-15 sec until whistling fades back in and runs bad again. It sounds like whistling is coming from throttle body but can't be sure as need someone to keep it running while I search for source.

 

Does anyone have full vac diagram for 87 they can give me please?

Edited by PeteyPathy
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I would replace all the vacuum lines, do one at a time, on vehicles this old, it's just better to replace them, a line that appears OK could be cracked or split on the bottom where you can't see it, the lines are cheap enough and most are the same size.

 

I can scan the vacuum diagram after work later, I have the FSM for the 87. THeir should be a sticker under the hood also.

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Haven't seen a sticker. Haven't really thought to look for one either though. I'm interested mainly in vacuum associated with the TB seems to be originating there hard to tell 100% though. The vac lines are all new already i found 1 that was too long and got against belt which cut hole in it, repaired that one. If you can scan vac diagram and maybe TB diagram that would be awesome! I'll PM my email. I'm just hoping against hope that it's not manifold leak. Though that will give me chance to fix couple of things that i couldn't get too cause under intake.

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Spray some brake cleaner or starting fluid on the suspected areas. The engine will rev if it sucks any in.

 

Are you talking about the anti-backfire valve on the front of the throttle bode under the air cleaner that's whistling?

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Ahardb0dy was nice enough to get me a working link for FSM. I'm now 90% certain my problem is VCV. Never would have found it without FSM THANK YOU!!!! It's either sticking open or spring is weak. After cleaning with contact cleaning spray it will now idle (barely)

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Looking into the throttle body to the right of injector is a port inside neck of TB reach a stiff piece of wire in there and push the plunger down. Its not vac line it's a primary vac port, allows unmetered air in large quantities. Truck behaves like it has collapsed intake gasket. But it passed the ether test, several times.

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I had never heard of the VCV until now, and looking at the manual, I have no idea what it's for. :scratchhead:

 

I saw a test on Youtube recently where the guy took a jar, put a piece of hot charcoal and some torn up cardboard in it, then hooked a hose from the lid to the intake manifold. He had another hose to blow air in through. It made gobs of smoke and found the leaks pretty quickly. Might help if your leak isn't where you'd think to spray ether.

 

Also you might want to take a closer look at the MAF. My friend's dad's Buick was running really lean, white spark plugs, a mechanic had told them the intake manifold gaskets were shot (common problem with that year apparently), but we couldn't find a leak. Turned out the MAF was so gunked up that it took several sprays of contact cleaner and gentle wiping with cotton swabs to get all the muck off it.

 

If cleaning the VCV helped, you may already be onto your issue though.

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Got a friends help, he put thumb over vcv idles perfect, take thumb off goes to crap. Went to u-pull it 6 pathys all 90 or newer ?

 

Cleaned MAF when i replaced TPS and CPS it didn't appear dirty or gummed up at all.

 

Update, i couldn't use loaner ride anymore so decided since I know whats wrong with it to go ahead and drive mine. It has decided to run right again all by itself.... Just like it decided to be stupid. Maybe i loosed up whatever was sticking vcv open or something... I don't know!

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