Trouble with rough idle 86 Pickup 22RE, 86k Miles
01-05-2017, 12:30 PM
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Trouble with rough idle 86 Pickup 22RE, 86k Miles
Hi everyone,
I am the second owner of a 1986 22RE SR5 Pickup with 86,000 original miles. I've been having a bit of trouble with a rough idle that I'm hoping to get some guidance on.
Info on the problem: The truck shudders at idle when warm despite the tachometer reading the proper idle speed (750) but it will occasionally drop down to 650, sometimes 600. If I listen to the exhaust I can hear this hiccup in it. I recorded the sound of the exhaust so you can hear it yourself (https://instaud.io/HmN). You can hear how it's not on a timed interval, that is to say it doesn't occur with reliable frequency, as in the recording right near the end it happens 3 times in quick succession. The hiccup seems to occur when the idle is high during warmup but I'm not 100% sure on that. This problem was present when I bought the truck 8,000 miles ago, but at that point it was very intermittent, occurring only once every week or so. Over time it became more frequent, up until now when it occurs constantly once has warmed up. The problem does not change when I pump on the brakes. I know that sometimes the brake booster can get a vacuum leak but I don't think that's the case here. My gas mileage seems to be okay (18-23 mpg).
What I've done: I did a tuneup shortly after I bought the truck (7,000 miles ago), replacing the distributor cap, spark plugs and ignition wires, and a new air filter. (Any chance something improper here could have caused the problem? It didn't seem bad after I did the tuneup and continued to get worse despite this change.) Just recently I ran a couple of cans of Seafoam through the tank as I thought maybe this problem was being caused by dirty injectors. So far none of this has made a noticeable difference.
Questions: What do you think is the problem and what can I do about it? My friend suggested that maybe cleaning the throttle body and the idle control valve would be a good place to start but I thought I'd ask here before tackling that. Is it possible that my idle is just too low and the tach is reading wrong?
Thanks!
I am the second owner of a 1986 22RE SR5 Pickup with 86,000 original miles. I've been having a bit of trouble with a rough idle that I'm hoping to get some guidance on.
Info on the problem: The truck shudders at idle when warm despite the tachometer reading the proper idle speed (750) but it will occasionally drop down to 650, sometimes 600. If I listen to the exhaust I can hear this hiccup in it. I recorded the sound of the exhaust so you can hear it yourself (https://instaud.io/HmN). You can hear how it's not on a timed interval, that is to say it doesn't occur with reliable frequency, as in the recording right near the end it happens 3 times in quick succession. The hiccup seems to occur when the idle is high during warmup but I'm not 100% sure on that. This problem was present when I bought the truck 8,000 miles ago, but at that point it was very intermittent, occurring only once every week or so. Over time it became more frequent, up until now when it occurs constantly once has warmed up. The problem does not change when I pump on the brakes. I know that sometimes the brake booster can get a vacuum leak but I don't think that's the case here. My gas mileage seems to be okay (18-23 mpg).
What I've done: I did a tuneup shortly after I bought the truck (7,000 miles ago), replacing the distributor cap, spark plugs and ignition wires, and a new air filter. (Any chance something improper here could have caused the problem? It didn't seem bad after I did the tuneup and continued to get worse despite this change.) Just recently I ran a couple of cans of Seafoam through the tank as I thought maybe this problem was being caused by dirty injectors. So far none of this has made a noticeable difference.
Questions: What do you think is the problem and what can I do about it? My friend suggested that maybe cleaning the throttle body and the idle control valve would be a good place to start but I thought I'd ask here before tackling that. Is it possible that my idle is just too low and the tach is reading wrong?
Thanks!
Last edited by Lozo; 01-05-2017 at 12:56 PM.
01-05-2017, 01:52 PM
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Idle issues for these trucks (in my experience as well as a few friends) seem to stem from intake systems. Throttle body and IAC cleaning are essential and will make a noticeable difference as that part of maintenance is often neglected. Cleaning the Mass Airflow Sensor will help big league. Make sure you use the proper cleaner.
Seafoam needs to be introduced through a vacuum line to obtain a noticeable effect, but this is dictated by what has already been done to the engine and/or how clean it is.
Another option is your PCV valve. Very overlooked and easy to replace. They cost less than $10.
I'm sure others will chime in with other suggestions but this combination solved my idle problem. I believe the biggest help was the throttle body cleaning as the throttle plate was not closing quite all the way from the crud that was built up. When I bought my truck there was a mouse nest and a cheap filter in the air box, it's a wonder nothing more serious happened.
Seafoam needs to be introduced through a vacuum line to obtain a noticeable effect, but this is dictated by what has already been done to the engine and/or how clean it is.
Another option is your PCV valve. Very overlooked and easy to replace. They cost less than $10.
I'm sure others will chime in with other suggestions but this combination solved my idle problem. I believe the biggest help was the throttle body cleaning as the throttle plate was not closing quite all the way from the crud that was built up. When I bought my truck there was a mouse nest and a cheap filter in the air box, it's a wonder nothing more serious happened.
01-06-2017, 01:52 PM
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Thanks, TacoTank. I will be removing and cleaning the throttle body this weekend, and replacing the PCV valve along with it. If that doesn't have an impact I'll move on to cleaning the IAC and MAF. Any tips on cleaning those? I haven't been able to find much info on it.
01-06-2017, 02:11 PM
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Not a problem. Make sure before you dive into it you get new gaskets for the throttle body. Not good to re-use them and they cost me less than a dollar.
With the age of your truck you may wanna just clean everything as a good measure.
For the throttle and IAC, just get throttle body cleaner. I used the 3M brand in a spray can. Runs about $10. The IAC is attached to the throttle body so you can separate the two once you get them off. I believe there's a How-To thread with pictures on here. Should come up in a search.
I know for a fact that there are threads for cleaning the MAF on here. Very simple, again though it needs to be a specific type of cleaner (electronic contact safe). CRC makes it in a spray can, runs about $8. Just be extremely careful not to damage or touch the sensors to anything as they are extremely delicate.
With the age of your truck you may wanna just clean everything as a good measure.
For the throttle and IAC, just get throttle body cleaner. I used the 3M brand in a spray can. Runs about $10. The IAC is attached to the throttle body so you can separate the two once you get them off. I believe there's a How-To thread with pictures on here. Should come up in a search.
I know for a fact that there are threads for cleaning the MAF on here. Very simple, again though it needs to be a specific type of cleaner (electronic contact safe). CRC makes it in a spray can, runs about $8. Just be extremely careful not to damage or touch the sensors to anything as they are extremely delicate.
