94 GMC surges when it starts in 1st and 2nd

Re: 94 GMC surges when it starts in 1st and 2nd

Postby 94 Van Guy [OP] » August 22nd 2010, 6:35pm

Leeann_93 wrote:Looks like it. And yes, that is the EGR.

Also looks like you need to clean up the throttle plate...


Again, thanks. The clean spot is where I rubbed it and it was soft and oily. Will clean the throttle plate at the same time as I check the CTS for vacuum lines that are broken, off or missing.
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Re: 94 GMC surges when it starts in 1st and 2nd

Postby Leeann_93 » August 22nd 2010, 6:55pm

The CTS doesn't have vacuum lines. It has an electrical connection.
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Re: 94 GMC surges when it starts in 1st and 2nd

Postby 94 Van Guy [OP] » August 22nd 2010, 7:27pm

Leeann_93 wrote:Stupid double post by the forum software again...


Thanks, :thumbup:

I read your last post, and the second, this one, was not there. Now it is... go figure.

OK then, no vacuum lines connected to the sensor, so the only thing to do is recheck all vacuum lines including the PCV valve as well. and read the data stream, by someone that knows what they are looking at. :shrug:

Off to a B-Day party, my Granddaughter is 16 today! Woo woo...
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Re: 94 GMC surges when it starts in 1st and 2nd

Postby Matrixx » August 22nd 2010, 7:28pm

Hi 94 Van Guy

I have to apologize here to VG. Your year (with the W motor), the CTS is located in a different spot than the 1996 and newer vans. Either way I was incorrect on both points. The 1996 and newer vans, the CTS is located just off to the side of the T-Stat housing not in it.

With your year, the CTS location is on the upper passenger side corner of the engine. I grabbed a diagram to show you just where it is. Again 94 Van Guy, my bad and here is the correction for it (diagram):
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Re: 94 GMC surges when it starts in 1st and 2nd

Postby 94 Van Guy [OP] » August 22nd 2010, 10:59pm

Matrixx wrote:Hi 94 Van Guy

I have to "Deeply" apologize here to you VG. Your year (with the W motor), the CTS is located in a different spot than the 1996 and newer vans. Either way I was incorrect on both occasions. With the 1996 and newer vans, the CTS is located just off to the side of the T-Stat housing not in it.

With your year, the CTS location is on the upper passenger side corner of the engine. I grabbed a diagram to show you just where it is. Again 94 Van Guy my bad and here is the correction for it (diagram):


No problems, all is OK. We don't worry about little the things. :rofl:

I have found the CTS, and have a photo. You know, without a photo... :thumbup: so for now, put it back togather and will wait for another day.

Thanks to all, you have been so helpful, I WILL, get to the bottom of this, period. :wave:
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Re: 94 GMC surges when it starts in 1st and 2nd

Postby Matrixx » August 23rd 2010, 9:54am

Thanks 94 Van Guy, I'm just working on to many different vehicles at the moment (Ford Taurus-Toyota 4-Runner-Toyota Cressida-Dodge Caravan).

It was the Toyota T-Stat housing that kept flashing in my head when I replied to your question, the Water Temperature Sensor for the Toyotas are located in the housing (a least with the ones I'm currently working on).

Time for a break, hehe.;)
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Re: 94 GMC surges when it starts in 1st and 2nd

Postby 94 Van Guy [OP] » September 12th 2010, 11:04pm

It's been a while, I have the doghouse off, have removed the PCV valve and have it in my hand. I cleaned it up with hot water and soap. I have checked to see if it holds a vacuum, it doesn't. when I create a vacuum on the end that goes into the valve cover, it leaks. I mean it never seals off completely. If I put pressure from the plastic side, the side the vacuum hose goes to, it leaks.

Should the valve close sometimes so that the vacuum will build up? Or should I just replace it?
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Re: 94 GMC surges when it starts in 1st and 2nd

Postby 94 Van Guy [OP] » September 13th 2010, 1:44am

Replaced the PCV valve, the hose that goes to the intake was new, solid and connected. Took the van for a ride and when it got to running temp, the same thing happened. I give it some throttle and the van surges, for the lack of a better word. Well it's a process of elimination. Now we know that the vacuum connection is solid. Checked all of the rest of the vacuum I could get to from the back with the doghouse off.

I am lost... what else to look for? I do know a honest Dealership I can take it to, just wanted to try to fix it on our own. Any other suggestions? As a recap,

When it is cold and I give it some throttle the van goes solid until it shifts into second gear, then it is solid and smooth.

After it gets to temp, the start from first I open the throttle a bit to get to speed, about 40 MPH,and then is like the throttle is opened a bit more then back then more and over until it hits second and repeats the same thing. I seems like the timing is being advanced and the retarded, over and over.

At freeway speeds the surging is still there and seems to have less power than it should have.

It runs rich and gets 13.3 MPG. Checked the codes, the SES light flashed once then twice, over and over.

The cruse control is OK at slow speeds, up to 35 MPH, but at freeway speeds when going up a hill, it kicks off.

The same thing happens at different amounts of throttle, not at just one place on the throttle.

That about it, is there any Ideas?
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Re: 94 GMC surges when it starts in 1st and 2nd

Postby 94 Van Guy [OP] » September 13th 2010, 7:18pm

Could the EGR cause the symptoms I am having?
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Re: 94 GMC surges when it starts in 1st and 2nd

Postby astroturf » September 13th 2010, 7:50pm

I would not rule it out.
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Re: 94 GMC surges when it starts in 1st and 2nd

Postby chevy57bert » September 13th 2010, 8:53pm

I wish I could help you Keith.. But I can`t..
You need the diagram to see what vacuum lines are connected when the engine is hot.
Look and test those hoses to find your BAD line....
Take them out one by one and inspect the hoses for wear / leaks / cracks..
Check the cruise control hoses and connections..

Any leaks at the manifold? EGR valve.? Is your Air filter tight?

Sorry it isn`t a DAF engine. I would KNOW :rofl: :rofl:

Good Luck Keith.... keep us posted.. :thumbup:
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Re: 94 GMC surges when it starts in 1st and 2nd

Postby 94 Van Guy [OP] » September 13th 2010, 9:08pm

Thanks Jim and Bert, I have replaced most of the rubber type but not the hard plastic type. I think those are next.
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Re: 94 GMC surges when it starts in 1st and 2nd

Postby chevy57bert » September 13th 2010, 10:31pm

94 Van Guy wrote:Thanks Jim and Bert, I have replaced most of the rubber type but not the hard plastic type. I think those are next.


And keep a eye on the where the hoses connect.
Don`t know the English word for it. we call it Pillar, they have some rubber grommet or copper gaskets to seal the seat..
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Re: 94 GMC surges when it starts in 1st and 2nd

Postby 94 Van Guy [OP] » September 18th 2010, 6:29pm

One thing I hadn't tried, and that was to open the throttle completely. I did just that last night. Found an entrence ramp to the freeway where no body was there and off we go! This was the first time I had opened the throttle and held it open until it shifted into third.

In first gear, all I could feel was acceleration.

In second gear the same, then it shifted into 3rd gear. I only left the throttle open for a few seconds more, I was at over 85MPH and thought I should shut it down. I can't say I could feel any surging during full throttle acceleration. (I feel as there was all of the power that these vans should have)

I do understand that during full throttle, the vacuum is at it's lowest, but just how that translates to the problem, I don't have a clue.

One more piece to the puzzle, hope that helps with the diagnosis.

Any thoughts?
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Re: 94 GMC surges when it starts in 1st and 2nd

Postby Looney Lenny » September 19th 2010, 3:44am

Sounds strage but I just bought my van (A 2000awd). Mine was doing the same thing. The throttle was erratic all over the place. I would set the cruise & the same thing would happen. It would kick off yet accelerate then deccelerate. It did this until the service engine soon light came on. My mechanic replaced the fuel filter & lines. The fuel filter was plugged with rust from corroding from the inside out. He also had to replace the "Filler Neck" to the gas tank as it had many pinholes rusted in it. (he told me that information gathered from the computer diagnostics told him to check for this condition). The filler tube was indeed a major player in the throttle being erratic. I had thought the cruise-controll cable had stuck & needed lubed as this would be the closest symtom description I could sermise. I had all the fuel,vacume, brake lines replaced. In the end the mechanic told me that the fuel filter being plugged in combination with the gas tank filler tube being rusted through was causing my throttle & shifting problems. My van runs fine now. I now have to replace the belts! Wife threw a P/S belt today.

Good Luck & hope it helps Ya!
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Re: 94 GMC surges when it starts in 1st and 2nd

Postby 94 Van Guy [OP] » September 26th 2010, 3:19am

OK, after replacing the sensors, same thing, surges as it has.
Pulled any stored codes, there were none.

Lets see what has been done in the last 700 miles.
New cap, rotor, plugs, wires
all new vacuum lines including the Check Valve,except for the hard plastic lines.
PCV valve and the big line for it.
Inlet Air Temperature Sensor
Coolant Temperature Sensor
Cleaned the Throttle Plate
Lucas injector cleaner, twice

It seems funny, when the engine is first started,and it is stone cold, it has more power and accelerates smooth and evenly.

After it has warmed up to operating temperature, the van becomes sluggish and starts to surge. The surging is at all throttle settings and all gears. At freeway speeds, the surging is still there, but not as noticeable, unless you are at heavier throttle and then it is very noticeable. If I stop at, say a store for a few minutes, the surging is gone for about 30 seconds or so, then returns.

I think I have checked everything and replaced some parts, that I was unable to check, that has been suggested. Have I missed something?

I think the only thing left to do is get it to the dealer and have them check the data stream to see what is happening.

Keith

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Re: 94 GMC surges when it starts in 1st and 2nd

Postby Phantom » September 26th 2010, 3:55am

Maybe the ignition coil is getting old and weak and starts to give a weaker spark after it has warmed up , secondary windings breaking down, then when stop at a store it has chance to cool down some, then warms up rapidly when driven?
Possible weak fuel pump surging in pressure range?
yea a real time diag while running should show what is causing the surging
Google all possible causes for surging for possible new ideas?
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Re: 94 GMC surges when it starts in 1st and 2nd

Postby 94 Van Guy [OP] » September 26th 2010, 4:04am

I did read something about the MAF/MAP. I wonder if that could do it?
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Re: 94 GMC surges when it starts in 1st and 2nd

Postby Phantom » September 26th 2010, 4:12am

I would have to read up more , been awhile since i had to replace one of those , they do deal with manifold vacuum , which does vary with rpm, I think it is the lower rpm the higher the vacuum and high rpm -low vacuum,
possibly partial clogged EGR passage /screen , I did not see that in the list of things done
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Re: 94 GMC surges when it starts in 1st and 2nd

Postby 94 Van Guy [OP] » September 27th 2010, 5:14pm

Phantom,

I have not done anything to the EGR.

I do have a new observation though. I was using the battery a lot today without the engine running. I decided to start the engine, idle the engine just a bit, to charge the battery. The engine was hot, as I had been driving around town, and about 20-30 seconds later, the engine started to slow down, almost to the point of stalling then back. The interval of the slow down and back, is the same as when I am driving and experiencing the "surging" problem. When at a very slight faster idle,(about 100 RPMs more) the problems continues until I release the throttle pedal.(it also does the same thing when the throttle is pushed faster, it's just not as noticeable) It then finds it's way back to an idle. At the idle position on the throttle pedal, the engine runs as smooth as glass.

This new observation seems, to me, to be different, instead of the engine speeding up then back, it the other way around.

Don't know if sheds more or a different light on things, but I thought I would get some feedback on this.

Thanks for reading and all the help yous have given me, I do appreciate your thoughts.

Keith
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