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89 high idle problems, surging, help!

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toppryority

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k5 350 high idle, replaced fuel sensor, o2sensor, new plugs and distributor, lines, new vacuum lines, coolant flushed, whats next? check engine light off and on, just cant get it right and running out of ideas..... replace ECM?

spits lots of fuel, surging idle and always runs high idle and runs higher as it warms. dual exhaust, heater does not work with blower on.

Any ideas?????? thanks
 
As long as you are throwing parts at it, try the idle air control valve (IAC). It controls idle speed via ECM input. Threads into the throttle body unit. Easy and fairly cheap to replace.

While you are at the parts store, pick up a gasket set for the throttle body and a couple cans of carb cleaner. Remove the t-body from the intake, take it apart and clean all the insides and passages with carb cleaner and an old tooth brush and you may need to dig out the PCV passages with a small screwdriver or pick set. Make sure to clean the IAC passages while you have it apart. Clean all the gasket surfaces and put it back together.

But, I suggest one thing before spending any more money on it. Do a physical check on the throttle blade operation. With the engine off open it and close it by hand while looking into the throttle bores. Make note if the blades are closing completely. Check for play in the throttle shaft. My original throttle body had worn shaft bushings. Worn enough that the throttle blades would not close completely causing a high idle, almost dangerously high. Quick and cheap fix is to swap out the unit with a good used one. But, you may be able to send it out and have the bushings replaced.
 
toppryority said:
k5 350 high idle, replaced fuel sensor, o2sensor, new plugs and distributor, lines, new vacuum lines, coolant flushed, whats next? check engine light off and on, just cant get it right and running out of ideas..... replace ECM?

spits lots of fuel, surging idle and always runs high idle and runs higher as it warms. dual exhaust, heater does not work with blower on.

Any ideas?????? thanks
Click to expand...

yeah, ya might wanna start with checking codes considering the SES light is going off..


http://www.cfm-tech.com/gm_tbi_trouble_codes.htm

as mentioned, idle and surging issues are often an IAC issue.. and that is a part that get's crudded up over time, especially if not running right...
 
Stop replacing parts.

What codes are you getting? Just as an FYI, the code doesn't mean the component is bad, just that the ECM is not seeing the values it expects from said sensor. But the codes need gone (as in problems fixed) before doing anything else.
 
my codes came back at 12, 13, 21, 22, 32, and 44. Surely I can't have all those problems after all the work I've done? Thoughts?
 
the 12 is the normal initial code. the 13 and 44 are probably related with an O2 issue.. even tho you did the o2, i doubt thats your major issue, just double check your connection for that..

EGR's are very common, they get carboned up.. that usually gives you off idle stumbling issues..

however the 21, 22 TPS codes are more than likely your biggest issue, that will cause ALL kinds of running/drivability issues...
 
Is the coolant full? ect cant get a good reading without coolant. Heater cant work without coolant.
 
Yep, just had coolant flush and fill so that's not it. Any other ideas?
 
toppryority said:
Any other ideas?
Click to expand...


:whistle:


the 13 and 44 are probably related with an O2 issue.. even tho you did the o2, i doubt thats your major issue, just double check your connection for that..

EGR's are very common, they get carboned up.. that usually gives you off idle stumbling issues..

however the 21, 22 TPS codes are more than likely your biggest issue, that will cause ALL kinds of running/drivability issues...
Click to expand...

using multimeter set to dc volts,
probe dark blue wire with needle probe(red lead), (black lead to ground)
ignition on, engine stopped
voltage should be around .5vdc.
slowly open throttle, voltage should increase up to 5 vdc at wide open throttle.
should be no flat or dead spots or voltage spikes.
 
Or, buy/make a cable, download winaldl, take your laptop out to the truck, and take a look at *everything*.

I haven't had any failed electrical parts, but while most all can be checked with a multimeter, it makes it quite easy with the cable/laptop.

You are dealing with a "computerized" system, sooner or later you will have to understand it to have a chance at fixing it.
 
toppryority said:
my codes came back at 12, 13, 21, 22, 32, and 44. Surely I can't have all those problems after all the work I've done? Thoughts?
Click to expand...


have you been unplugging stuff while it is running or the key is on?

I would clear codes, and run/drive it a bit and see what comes up first.
 
dyeager535 said:
Or, buy/make a cable, download winaldl, take your laptop out to the truck, and take a look at *everything*.

I haven't had any failed electrical parts, but while most all can be checked with a multimeter, it makes it quite easy with the cable/laptop.

You are dealing with a "computerized" system, sooner or later you will have to understand it to have a chance at fixing it.
Click to expand...

yes, and if you are not willing to get the correct tools, you would be better off paying some one to fix it. It will save time, aggrivation, and probably money.
 
i will reset everything today (by unplugging battery cables) and then run around and see what codes are and then post. thanks all, i am hoping to get this corrected cause its really driving me crazy!
 
okay, reset everything and codes came up clean at first. idle was correct, ran around and it was fine. shut off and then refired and within 3 minutes of startup, engine began to hesititate and a small low then normal idle. then she surged and began running high idle again. let run and surged a couple times and then set in with the extremely high idle.

ran through codes again and it came back a 22

ideas?
 
tps, get a volt meter and check for 5v reference, ground and voltage increasing smoothly from .6 ish on up, on the three wires.
 
so what you guys are telling me is there is a loose ground wire somewhere correct? I am no mechanic but try to be a fast learner. Thanks
 
you need to test the TPS with a meter like I posted earlier..
 
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