Intake tube showed up today. I installed it, cleaned the throttle body a little more and fired it up. I let it run for a while to get some of the injector cleaner through the system. I dare say it's idling better now. Has anyone ever had issues with their dashpot affecting off throttle idle? I'm wondering if when it's going back to the throttle stop that the dashpot might be sticking, causing it not to return to proper idle position? Just a thought of a frustrated 80 owner...
So we aren't really dealing with an idle only issue.
Time to back up and get some more background info. Forgive me if I missed some of this in earlier posts .....
Was the idle problem sudden or did this come on slowly?
Has it ever been an idle only problem or has there always been some stumble on acceleration?
So, no single event you can point to when it started? (eg after filling up with gas) or is this since you have had it?
I'm still a bit surprised it hasn't tossed a code. Have you ever had a CEL and, if so, what code?
You say it cleans out on the top end .... do you mean it has a smooth cruise at 2200rpm or things don't butter up until 4000?
Since you have already replaced the TPS it is time to focus on the harness. This is a hated job but is the next logical step. With engine cold you will need to climb up in there and get to the harness close to the EGR valve. Unwrap and carefully check for wire damage.
It's always had an idle issue, I've just put up with it. The stumbling and shuttering under load has just started recently. I took the truck to a friends house to use his timing light. We set it at 6* in service mode. I drove it home and that when the hesitation began. It had started a weird kind of rhythmic shuttering a few weeks back though when it's in higher gears. They are two different symptoms. One is obviously engine related, but the shuttering seems more transmission related...but it's hard to tell. The only codes the truck has ever thrown are O2 sensor codes. Both of those are new denso units. I haven't noticed what rpm it clears up at, it's more of a throttle position thing. I.e. If I give it half throttle or more it accelerates smoothly. The harness near the EGR is sans insulation. Looks like someone has looked at it before. Who knows how long it has been that way. This thing was and still is a basket case. I got a deal on it but I'm paying for it now...
New injectors on the way, so I started taking things apart to get ready for that. I found a very loose bolt on the EGR. That would explain a lot of the issues as well as the exhaust leak I could never pinpoint...maybe. The main harness looks good by the EGR, I'll check all the wiring to the injectors when I get the upper intake off tomorrow hopefully.
Good deal. This isn't a slam dunk as far as diagnosis is concerned but the description you give points to either the TPS or to a vacuum leak. I would not rule out the 2nd TPS being bad but it's highly unlikely. Running on 5 cylinders can create the condition you describe and it is possible for that to happen and for cylinder 6 to clean up and start firing at higher rpms ..... again, just not likely. Injectors can do this but injectors are not highly prone to failure.
If the Charlotte crew is planning to have a club meeting soon it may be worth the drive to get another set of ears to give it a listen.
I actually found a vacuum hose last night as well that I had blocked off but it had a hole in it. The injectors look original so they will get replaced anyway.
Still waiting on injector plugs. I did the PHH earlier this year. It had been done before but they used crappy hose so I put a silicone kit on it. I wasn't going to do the lower intake gasket, but I guess it makes sense to do it while I'm there. Walking out to do that now...
Still waiting on injector plugs. I did the PHH earlier this year. It had been done before but they used crappy hose so I put a silicone kit on it. I wasn't going to do the lower intake gasket, but I guess it makes sense to do it while I'm there. Walking out to do that now...
Sounds like you're on top of it. Nice going. Only sad part is you've changed too many variables now to know which one is the fix, but at this point you probably don't care.
Yeah at this point if it's fixed, I'm happy. I'll be happy knowing all those new parts are on there so I hopefully won't have to tear back into it anytime soon!
Apparently the PO tightened the fill plug bolt too much on the tcase and cracked it where the bolt seals to. I've had it sealed up with black rtv since I've had it. The bolt will only go in hand tight plus a little. It acts like its stripped because of the cracks. It's had a steady drip the whole time. I guess I'll have to pull the back of the case off and try to have it welded.
Got it back together earlier today, no noticeable improvement. Thinking of moving it to the backyard and lighting it on fire. I ordered a new TPS. If that doesn't fix it, I may go through with said plan.
