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Warm up trouble - almost cuts out on me

S

Steve88

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Just started within the past two weeks. Has been fine otherwise:

For first 5 - 10 minutes of driving if I step on it at a light it'll almost die on me. Once I get going it sounds/feels o.k. Just at take-off. I have to pump it a bit to keep it from stalling out, or just take off very slowly. Once warmed up it seems o.k. Haven't changed anything on it recently.

Any ideas? Fuel filter or pump? (but it's o.k. once warmed up, so I don't think it's that.)

thanks!

88K5 stock 350TBI, 111000 miles.



<font color=red>Steve88</font color=red>
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88K5 Silverado
 
mine did the same, gradually got worse, and it was the fuel filter, my gas tank had rust in it and it began to clog the filter slowly, i had to have the tank cleaned and a new filtr put on and that fixed it
Kelboski....mines a 4 barrel though...not a tbi
 
I might do the filter this weekend for the heck of it. Probably needs it anyway. Can't understand why it would work ok after warmup though. But what do I know...thx

<font color=red>Steve88</font color=red>
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88K5 Silverado
 
i don't understand the warm up thing, since its a tbi....someone here will know though. sorry i'm not much help
Kelboski
 
Well here's an update:

Replaced the following: Dist cap and rotor, fuel filter, O2 sensor, upper and lower air-cleaner gaskets. Checked all the vacuum lines, everything looked ok. Pulled the computer codes. 44 came up (which says lean mix reported from the O2 sensor.) Would this cause a bog when it's warming up? Remember it's a TBI. I'm going to do a diagnostic on the new O2 to make sure it's working. Supposed to read 100 - 1000 millivolts when running and warmed up.

Any other ideas?
thx

<font color=red>Steve88</font color=red>
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88K5 Silverado
 
What's a CTS?

To answer your other question, the Service Engine Soon light only came on one time, last week, for a minute and I hadn't seen it before then - ever, nor have I seen it since then.

(Already changed the fuel filter...)

<font color=red>Steve88</font color=red>
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88K5 Silverado
 
Ahh. OK. For $6 it can't hurt to change it.

Hey AZBLAZER, shouldn't you be at work? Heh-heh!

<font color=red>Steve88</font color=red>
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88K5 Silverado
 
By the way - where does it go and what does it do?

My engine seems to be cooling fine, and the temp gauge is reading fine.

<font color=red>Steve88</font color=red>
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88K5 Silverado
 
Steve,i had similar problems with my '88 and after replaceing a number of things...fuel filter etc...it turned out to be the egr valve......just my 2 cents...reach under the egr and try to move the diaphram with your finger tips if it is sticking or hard to move then it prolly needs to be replaced....hope that helps..like i said it worked for me but the other fellas are also correct.
 
Yeah, I took a good look at my Haynes manual last night, and along with the EGR valve, and the CTS, I've got a whole bunch of other things I can now check for this weekend. Thanks to all and I'll provide an update when I figure it out.



<font color=red>Steve88</font color=red>
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88K5 Silverado
 
you're spark control module, or a bad ground could do it also.........the codes would tell you though
kelboski
 
Plot thickens...

I checked the EGR valve this morning and it moves freely, BUT found that the other end of the vacuum line was connected to a broken nipple. And we know how much those hurt!

No really, I have the following 2 questions:
1) What is that thing it's connected to called and/or part # for it? (EGR solenoid?) Autozona and Checker couldn't tell me over the phone. What should it cost? It has the vacuum line from the EGR connected to it, and a vacuum line from the TBI connected to it, along with a wiring connector.

2) There is actually a third vacuum nipple on this same thing, that was above the broken one. Is there something (even a plug?) supposed to be connected to this? I don't see any dangling hoses.

Thanks!


<font color=red>Steve88</font color=red>
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88K5 Silverado
 
I think the x-tra port on the EGR solenoid is just an atmospheric vent. When it's on, the solenoid connects the EGR valve to the vacuum source from the throttle body. When it's off, it connects it to this vent. If it just blocked it off, the EGR valve would not close, or it would close very slowly. If I recall, on my truck, the vent had a foam filter over it that looked like a little microphone cover.

Tim

1970 Blazer CST 4X4 350 SM465 NP205
1987 Suburban 4X4 350
1988 Chevy Pickup 4X4 350
 
OK. Well I did in fact replace that EGR solenoid, and even took the EGR itself off to check it's usability. That was over the weekend and I didn't see any positive results from the new EGR solenoid, and the valve itself seems to be working properly. Even tested my O2 sensor (remember I just bought it) on my multimeter and it read as it should have (.1 - 1 volts).

Then I went ahead and changed out that CTS (coolant sensor) and wah-la problem went away. Sure enough, like AZBLAZER and the others had mentioned, it seemed that even though I wasn't pulling the code for a bad CTS, the CTS must have been reporting a bad temp to the computer and leaning out the mixture to the point that it would cut out when I needed it at take-off.

So the $9 CTS ended up fixing the problem from what I can tell. Thanks all and hopefully someone besides me will learn from this post.

<font color=red>Steve88</font color=red>
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88K5 Silverado
 
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