87' chevy pickup problems

[.38 special]

Anyone know anything about TBI 350s?

I have a very high idle problem. 1800rpm
I have an otc 2000 scantool.
what do I put in for the vin #?
my engine code is K, but it has to be a number for the otc.
I can't find any vacuum leaks and the aic motor is working as far as I can tell.
is there a sight to get the otc codes and what the sensors should be set at?
Any info or ideas to fix it would be appreciated.

 

[Reaper]

have you tried using a hammer to adjust the idle. i was under the impression that in 87 they still had a rochester on the trucks? who knows i drive a 79


Dathan

 

[.38 special]

87 was the first year of the throttle body for the trucks.
-Thats why I bought it. I forgot how to tune a carb after owning a turbo regal.

 

[myclone]

Originally posted by .38 special
87 was the first year of the throttle body for the trucks.
-Thats why I bought it. I forgot how to tune a carb after owning a turbo regal.

Yep, 87 was the first year as buds dad has one he bought new.

Have you pulled the IAC and cleaned it and its bore with carb cleaner? If not then turn the key on but dont start the eng, wait a few seconds for the IAC to retract, then unplug and remove (turn the key off too). Clean the IAC and the IAC bore in the TB then reinstal the IAC and fire the truck back up. If that was the prob then the idle will be high for a few seconds then should settle down.

If that doesnt fix it then check/replace the TB to intake gasket as TBI trucks with a lot of miles tend to develope vacuum leaks there.

Also, with the age/milage make sure the vacuum hoses are in good shape. Something Ive learned is just cause they look good doesnt mean they are as they develope tiny cracks from underhood heat/age.

Lastly, make sure the MAP isnt on its way out as other than a IAC or vacuum leak it is the only thing that will usually cause a high idle in a TBI engine.

HTH

 

[Buick From Hell]

I have a '92 Winnebago with a TBI 454, I've had the same high-idle problem since I bought it 2-1/2 years ago...the only suggestions above that I HAVEN'T tried is changing the map sensor. Maybe I'll try it, it gets old throwing the thing into neutral just so I can STOP the thing!

 

[.38 special]

The AIC was extremely clean.

All of the vacuum lines where good, but when I pulled one, it didn't seem to be sucking. That probably has something to do with it.

I just had the throttle body off and replaced the gasket should I have used some silicone?

Also what should the tps be set at, a manual said .41, but that made the idle even higher, so I set it back at .80 and I know that isn't right.

Does anyone know how to use the otc2000 on this thing, or where I can find out, or even a good message board for this kind of thing?

 

[steve hughes]

Don't know about the otc. If you have Turbolink you can use it on your truck. Make sure the throttle blades are actually closing all the way. Might be bent, loose or binding. Pull all the cables off and try it. Maybe a bad egr valve gasket createing a vacuum leak.
I think Lee Thompson uses an otc. You might ask him.

 

[49-blues]

try checking idle air control or the actual injector unit-went bad on my friends suburban and quite expensive.

 

[myclone]

Originally posted by .38 special
All of the vacuum lines where good, but when I pulled one, it didn't seem to be sucking. That probably has something to do with it.

At idle you should have full manifold vacuum at the MAP sensor so if there is low/no vacuum there that is more than likely the prob. If the truck has a lot of miles (which Im assuming it does considering the age) then make sure the vacuum port to the MAP isnt plugged with sludge/deposits.

I just had the throttle body off and replaced the gasket should I have used some silicone?

Ive never had to use silicone on a TB to intake gasket on a TBI vehicle and dont personally see the need for it unless either the TB or intake is extremely warped.

Lastly, as was mentioned make sure the throttle blades arent being held slightly open by build up inside the TB bores.

I wish I could help you on the TPS setting but the only TBs Ive messed with were ~90s which, if memory serves me correct, werent adjustable.

BFH,

You still havent found the idle issue with your mobile house? I know you tried just about everything else but have you thrown a junk yard ECM or new PROM in it?

 

[.38 special]

The vacuum port for the map--is that the hole that looks like there should be a vacuum line on it. It looks like it had a screen on it at one point. Kinda like our boost selonoid right.
Thanks for all the help.
Does anyone know a website for the otc or older trucks?

 

[.38 special]

Steve,
How do I get ahold of Lee Thompson?
What is his screen name?

 

[.38 special]

I found Lee's profile.
Also disregard what I said about the map. I was looking at the egr selonoid.

I think I got it fixxed. There was a leak in the tb to intake gasket. All I had to do was tighten it down. But now it is idling too low, I'm resetting the AIC now.

Thanks for all your help.

BFH, I think I have a spare MAP. It cam out of a normal regal. It worked for my truck. If you find that that is your problem, I don't mind sending it to you.

 

[2quiktocare]

Hey .38, Go ahead and replace that gasket. If it was leaking, it well come up again on you very soon. Don't use any silicone on it at all. The gasket will seal properly without it. You should service the IAC solenoid while there also. If the housing has a yellow sticker on it, don't clean it though. GM made a "self cleaning" part in later models and if has been replaced, you will possibly damage it if you use any cleaners on it.


Mark

 

[.38 special]

The gasket is only 2 days old. I just didn't tighten it down all the way. The reason I had it off was I broke a bolt off in the tb when adjusting the TPS. So, I had to drill and tap new holes. Then I guess after breaking that bolt I was scared to really torque on the Tb hold down bolts.

But it must have had a leak in the old tb gasket, because I've always had a high idle. Also, my brakes work alot better, since I'm finally makig some vacuum.

Now how do I reset the IAC. It idles too low now.

 

[arista5]

sent you a PM

 

[Scott King]

That OTC 2000 must be about the same age as the truck. The number you need for engine code K should be 20.

 

[Buick From Hell]

myclone--
Haven't touched the computer yet (haven't even FOUND it yet, that's how hard I've looked, LOL)...however, if I drive 60, I can get better than 10 mpg, driving to Vegas and back @ 75 the thing got nearly 9 mpg, and I get about 6 mpg pulling my 25' boat! --not bad for a 10,500 pound 'mobile house', so I'm leary of messing with the computer! The only other issue besides the high idle, is that it acts a bit lean at WOT, like, it'll seem to pick UP a bit of power if I let OFF the gas a bit...the good mileage and the lean WOT leads me to believe that MAYBE someone installed a 'gas mileage' chip in the ECM, and IF so, maybe it's causing the high idle(??)... (PS about the lean, I hooked a voltmeter to the 02 sensor, and climbing a slight grade in 2nd gear at roughly 4000 rpm, reading was a fairly steady 750-780 mvlts, is that in the ballpark?)

I even removed the plug that covers the throttle blade adjustment screw...when I turned the screw out, it slowed right down, and idled perfect! --for about 2 minutes, then picked right back up again! <sigh> OH, and I haven't checked vacuum at the MAP, I should probably do that, yes? It's all covered up at the moment, but I have to take it into the body shop in about 3 weeks to fix what the deer did to it so that'll be a good time to do a vacuum check...

.38 special, I'll take that MAF if you want to send it to me, I'll trade some dress-up trinkets for it!