1987 Chevrolet 350 tbi high idle

[iamtherealJayy]

As I said in my other thread, idle is off again.. it was sitting around 1200 majority of the time and got down to 900ish was the lowest I saw today, and it still doesn’t drop rpm when shifting. It stays at 1500-1600 with the clutch in..

 

[AuroraGirl]

As I said in my other thread, idle is off again.. it was sitting around 1200 majority of the time and got down to 900ish was the lowest I saw today, and it still doesn’t drop rpm when shifting. It stays at 1500-1600 with the clutch in..

well this is computer controlled and have you set the idle per the procedures...... and timing.... if those things are NOT in spec, you will not see your idle be right, Period. Im sorry but I dont know what else to say, we are all trying but throw us a bone.

 

[iamtherealJayy]

I haven’t touched anything, timing still locked at 0. The truck has always stayed higher in rpm when shifting but it was lower than today. Truck hasn’t been driven much this year, but it sucks everytime I think it’s getting better I find four new problems.

 

[gmbellew]

hit up the drivability manual and check all the things in the "incorrect idle" part of Section 2. I would also wiggle the harness around to the various sensors while idling to try and rule out a strange wiring or connection issue.

 

[iamtherealJayy]

Link the manual? Please @gmbellew or point me in right direction? Is it something I can just google or a physical book I need?

 

[gmbellew]

https://www.gmsquarebody.com/threads/1973-1991-service-manuals.14499/

scroll down to your year and click the driveability manual.

 

[iamtherealJayy]

Much obliged I’ll read up.

 

[iamtherealJayy]

Newest info, I just tried to jump the k10 with my truck and I connected jumper cables to k10 first then positive on my teuck and when I touched the negative it sparked and my rpms dropped and the truck almost stalled so I quickly yanked it off and my truck revved way up. What’s the possible problem here? Why would my rpm drop so drastically that the truck basically stalled, it shook the whole truck. Why did the jumper cables spark? They weren’t crossed so don’t ask lol. I’ve used the same cables for years kinda crazy that just happened.

 

[AuroraGirl]

Newest info, I just tried to jump the k10 with my truck and I connected jumper cables to k10 first then positive on my teuck and when I touched the negative it sparked and my rpms dropped and the truck almost stalled so I quickly yanked it off and my truck revved way up. What’s the possible problem here? Why would my rpm drop so drastically that the truck basically stalled, it shook the whole truck. Why did the jumper cables spark? They weren’t crossed so don’t ask lol. I’ve used the same cables for years kinda crazy that just happened.

It sounds like it possibly was too much load for your alternator, but it could maybe mean the truck had a short somewhere. unhook the k10s cables and then try to boost the battery. if you still see a drop, id try another vehicle to jump or battery, if you dont have the same reaction id suspect a failed battery, shorting inside maybe. you have another battery you can boost?

 

[iamtherealJayy]

The battery in the k10 is old not sure how old since I snatched it out of my first truck since it got totaled, long story.. wasn’t my fault and I walked away from it is what matters but. I’ve had issues jumping off this truck before, the first time I ever tried to jump off the k10 I used my truck and when I went to crank the k10 it was turning over but my truck stalled. The 87 fired right back up (this was still during high idle times so it had enough rpm to keep alternator moving at 1200+ rpms) so I let it sit like that for a few minutes and then I cranked k10 again and boom everytime my truck would drop in rpm with the extra load on battery and it ended up causing my battery to tap out and I had to take it to Walmart and have them charge it because it died and wouldn’t take a charge or anything. $140 battery and I’ve had a lot of trouble out of it.

 

[AuroraGirl]

The battery in the k10 is old not sure how old since I snatched it out of my first truck since it got totaled, long story.. wasn’t my fault and I walked away from it is what matters but. I’ve had issues jumping off this truck before, the first time I ever tried to jump off the k10 I used my truck and when I went to crank the k10 it was turning over but my truck stalled. The 87 fired right back up (this was still during high idle times so it had enough rpm to keep alternator moving at 1200+ rpms) so I let it sit like that for a few minutes and then I cranked k10 again and boom everytime my truck would drop in rpm with the extra load on battery and it ended up causing my battery to tap out and I had to take it to Walmart and have them charge it because it died and wouldn’t take a charge or anything. $140 battery and I’ve had a lot of trouble out of it.

i bet you have an issue with it, a truck in accident probably was hard on the insides. the lead plates cant touch eachother and the plastic case is what spaces them.

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[iamtherealJayy]

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It was just a slight fender bender. With a bed full of styrofoam. Gravel truck didn’t stop at intersection and tboned me. Less than two weeks after graduation. Drove truck home still in search of a cab. 159k miles.

 

[iamtherealJayy]

Alright I’m still having issues, the truck hasn’t stalled in a while, but if I’m going down the road I can push the clutch and the rpms don’t drop for a few seconds and they slowly go down. The truck majority of the time idles correctly once warm, but it takes a while for it to drop down. Say I’m driving and throw it in neutral to stop the truck will still be around 1200 by the time I come to a stop, and around 800 by the time I take off again. I’m not sure if this is like an advance weight sticking in the distributor or a different vacuum leak ir something. I have no idea, but it’s starting to bother me more for some reason. It isn’t hard to shift I can go through the gears no problem and the rpm drops once I’m in the next gear but it doesn’t drop if I push the clutch in or pull it out of gear. At least not for several seconds.

 

[AuroraGirl]

Alright I’m still having issues, the truck hasn’t stalled in a while, but if I’m going down the road I can push the clutch and the rpms don’t drop for a few seconds and they slowly go down. The truck majority of the time idles correctly once warm, but it takes a while for it to drop down. Say I’m driving and throw it in neutral to stop the truck will still be around 1200 by the time I come to a stop, and around 800 by the time I take off again. I’m not sure if this is like an advance weight sticking in the distributor or a different vacuum leak ir something. I have no idea, but it’s starting to bother me more for some reason. It isn’t hard to shift I can go through the gears no problem and the rpm drops once I’m in the next gear but it doesn’t drop if I push the clutch in or pull it out of gear. At least not for several seconds.

87 tbi distributors are known to be wonky
It still sounds like a improper idle set to me, the air flow with closed throttle is enough that the engine keeps more rpms. but then again i dont think it would make sense to drop instant with clutch press, since the engine has to respond to no load (no clutch pedal sensor like the throttle, if that makes sense)
and a load being lifted from it would free it up id think

 

[gmbellew]

I'd try to read up in the manuals about how the manual transmissions are supposed to work with engine RPM.