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1994 chevy 2500 Emission problems / stalling
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ahssell
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Jan 27, 2012, 10:13 PM
Post #1 of 14
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1994 chevy 2500 Emission problems / stalling
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I purchased the following truck.
1994 chevy c2500.
5.7 V8
automatic
187000
The truck failed a state inspection ( HCs are too high ) I knew about this when I bought it.
I understand it is running to rich
I have a AUTOXRAY Scaner, I hooked up to the truck.
No fault codes
And from what I can tell everything is operating normally ( by the book )
The stalling occurs when you accelerate it doesn't die just a loss of power and then picks back up.
Here is my plan.
Replace spark plugs, fuel filter, air filter
Check Timming
Any other suggestions?
Allan
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Tom Greenleaf
Ultimate Carjunky
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Jan 28, 2012, 3:14 AM
Post #2 of 14
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Re: 1994 chevy 2500 Emission problems / stalling
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With a pre OBDII vehicle that stalls (not normal) with no codes found I'd be looking for vacuum leaks and clean throttle body.
No problem with replacing the parts you mentioned as you then start your own history on a newly acquired vehicle. Go for quality for filters and OE for plugs note condition of each old plug and if not uniform with others note which cylinder as that could save time later if needed.
If a check engine light is ever on there's something lurking that is noted but OBDI may not target an area if intermittent.
5.7s and others have had intake gaskets and parts issues for quite a while now and a place to check out,
T
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Hammer Time
Ultimate Carjunky
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Jan 28, 2012, 4:10 AM
Post #3 of 14
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Re: 1994 chevy 2500 Emission problems / stalling
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High HC does not mean it's running too rich. It means it is not completely burning the fuel for some reason. You may be on the right track with ignition and vacuum leaks.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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dr.donut
User
Jan 28, 2012, 6:22 AM
Post #4 of 14
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Re: 1994 chevy 2500 Emission problems / stalling
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check for a motor to chassis ground, a braided wire
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ahssell
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Jan 28, 2012, 7:16 AM
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Re: 1994 chevy 2500 Emission problems / stalling
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Thanks for the reply. I am planning on looking at the Throttel body very closely. I have spray carb cleaner to address that issue. I have been reading that the IAC valve may be sticking or dirty will look at it real close. At this time, I had not planned on pulling the throttle body off but maybe something that I need to do in the near further.
I understand about the intake leaks. ( I had one that had that problem before ) I found that with a can of starting fluid sprayed around the intake manifold while the engine is running.
Now about the vacuum leaks. How is the best way to find them? It seems to have vacuum hoses everywhere.
I did not say everything I was going to do. I always do the following on any used vehicle, I buy to get a base line for maintenance.
Change the following oil&filter, filters, rear end oil, transmission fluid, clean the battery termanils, flush the radiator. And start a log book for maintenance completed ( I am an aircraft Mechinace )
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Discretesignals
Ultimate Carjunky
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Jan 28, 2012, 7:36 AM
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Re: 1994 chevy 2500 Emission problems / stalling
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IAC isn't going to cause it to stall on acceleration. Look at your scanner and watch the block learn and integrator. Also do a TPS sweep test and make sure you don't have any dead spots. If you can post some data snapshots, we may be able to pick something out from it. If it hasn't had a tune up, probably wouldn't be a bad idea to give it a full one including plug wires, cap, and rotor.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Jan 28, 2012, 7:38 AM)
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Tom Greenleaf
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Jan 28, 2012, 7:45 AM
Post #7 of 14
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Re: 1994 chevy 2500 Emission problems / stalling
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Finding Vacuum Leaks Basic:
DO NOT USE STARTING FLUID AS IMO IT'S TOO FLAMMABLE.
First look for any vacuum hoses or lines that are damaged or outright broken, cracked or not looking good.
Without engine too hot I use carb cleaner sparingly at suspect gaskets and areas and stress sparingly as it too is flammable. Idle would change for better or worse when you find something.
Haven't done it but plain water would be safer and if not equipped or don't know how get help. No fires please!
You might hear one. Others have used talcum powder - I haven't.
If nothing found the old spark plugs (already said) may show a problem and would go on to investigate why which could be improper spark, improper fuel delivery and a host of things but begin with basics,
T
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ahssell
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Jan 28, 2012, 10:25 AM
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Re: 1994 chevy 2500 Emission problems / stalling
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1-28-12 latest update
changed oil filter , rearend fuild , fuel filter , radiator flushed . Transmission serviced ( will take to trans mission shop and have fuild and filter changed )
Went ahead and had emission test run it passed . so now just working on hesation problem .
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Tom Greenleaf
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Jan 28, 2012, 2:54 PM
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Re: 1994 chevy 2500 Emission problems / stalling
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I do suggest keeping a book on what was done by miles and date as you just got this. Great that emissions passed and perhaps just using it some will bring out any gremlins.
Hesitation: Have you done plugs yet as you said up top? Already said they tell a story and if you take them out to even check IMO it doesn't make much sense unless somehow you can find out they are already new to put new ones in.
Hesitation II: You say it snaps out of that mode and runs fine again suggesting something is slow to react to your driving request and load. Things like TPS EGR could (about anything could do something) be involved. Do yourself a favor and put a drop of PB on nuts, bolts and fasteners to things you may need to do to make it easier and not break stuff hopefully later on. Fuel pressure may be right on the edge of the low range and so on.
Throttle body cleaned up yet? Put that on the list.
The trans service? Can be argued that changing fluid and filter will either help extend its life or bring out a problem. I take that gamble with my own newly acquired vehicles almost all purchased old and with miles and if plans are to keep it then let it blow up now not just to sell it with a pricey repair just to do so,
T
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ahssell
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Jan 28, 2012, 4:54 PM
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Re: 1994 chevy 2500 Emission problems / stalling
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I have changed the plugs and inspected and rerouted the wires. They were replaced three months ago along with the plugs ( I did not like the way they had them routed they were loose and could fall down and touch the exhaust. They are all secure and routed neatly )
The plugs that were removed, they were all whiteish colored one had a white crusty deposit. However, all were very clean no oil fouling ( looking at the wires. I was afraid that maybe they didn't use anti seize, but they came out clean )
I cleaned out the throttle body.
The Hesation is still there. If you slowly increase the gas from a stop is when it hesataes. If you get on it no hesation felt ( if it was a carburetor I would look at the accelerator pump )
I removed the instrument cluster, and the fuel gauge will move but always shows way over fuel.
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ahssell
Novice
Jan 28, 2012, 5:06 PM
Post #11 of 14
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Re: 1994 chevy 2500 Emission problems / stalling
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the integator reads 128
block learn reads 134
not sure how to do a tps sweep
at idel
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Tom Greenleaf
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Jan 28, 2012, 9:05 PM
Post #12 of 14
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Re: 1994 chevy 2500 Emission problems / stalling
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Notes:
Was that one plug a one with a plug wire touching exhaust manifold? I question integrity of that just because of that even if just a few months old.
TPS - I'd just look for a smooth sweep of ohms with no glitches of flat spots in its travel from idle to WOT - engine off.
Back - those flake(s) may be elsewhere in that cylinder. Generally a good run would clear them out if not being replenished with a fault.
Rerouting wires isn't a good idea. They should be as originally placed.
Use of anti-seize (silver stuff) if overdone can be a problem if all over the plug and on your fingers not good. Just a smear on just the threads as taper seated plugs rely on that to stay put.
Mark that cylinder that had the flake(s) for reference. Three months is too fast IMO for much of anything to show up,
T
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ahssell
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Jan 28, 2012, 9:32 PM
Post #13 of 14
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Re: 1994 chevy 2500 Emission problems / stalling
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I will check the TPS ( can I probe the back shell or should I remove the conector )
The wire that was close to the exhaust was another cylinder ( not touching ) and the wires were not in the factory wire holders just lose i routed them where they are in the factory holders
I sprayed the intake with carb cleaner no change in eng rpm. I inspected the vacum lines for obvisus problems and sprayed them with carb clener as well.
I didnt check the timming yet Should I ?
I am thinking its more of a fuel issue do you agree ?
I may need to replace the float anyway so I will do the pump at the same time.
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Tom Greenleaf
Ultimate Carjunky
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Jan 28, 2012, 9:58 PM
Post #14 of 14
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Re: 1994 chevy 2500 Emission problems / stalling
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TPS should be like a home dimmer switch. I don't have ohm specs but should be smoothly reflecting just what it is a "throttle position sensor" and forget the fuel gauge for now but do take a fuel pressure reading.
The plug wires being all over the place is hack work of course. Do they say what brand or any info on them? If someone put real cheap wires on it not to spec and length for the application I don't like that.
Old saying "The joy of low price is long forgotten when the pain of poor quality sets in" applies to many things,
T
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