1996 Sho... Idle surging/jerking.

[frankanthony]

I finally completed a 2 week long project on my car and have only been driving it for 3 days. The current issue that I am having is when idling the car will sometimes "bounce" from 600 to 800 rpm but sometimes it will sit solid at 600 rpm and act normal. I also discovered today that when I am idling and turn on the AC it will immediately rev up to 1k and then "bounce" again and sometimes create a more intense jerking feeling which I don't think i have experienced with the AC off. The AC rarely works and I was going to attempt to recharge it this week but I figured I should look into this issue first incase they are related. Btw putting the car in P - R - N - 3 - 2 - 1 with my foot on the brake doesn't seem to change anything. Thank you for your time and help!

Here is a list of repairs/changes to my car in the past 2 weeks. Thanks to the help of previous posts and articles in this forum! :thankyou:


Car repairs... Replaced transmission and torque converter (used 87k), New Magnaflow exhaust, new O2 sensors, new flex pipe, new front wheel bearings, new drivers abs sensor, new front left upper strut mount and bearing, new front sway bar links, front brakes, new transmission lines, new power steering line, power steering fluid flush, new right outer CV Joint boot, new starter relay, removed saxacone, new air intake accordion tube, new air filter and pollen filter.

 

[three50one]

http://www.v8sho.com/SHO/ACClutchAdjustment.htm
May not be the cause, but you can search broomstick test on here and go from there.

It either sounds like a slight miss or a vac leak at idle though. Make sure all of the electrics are clean and tight as well. It's easy to knock things around while doing all that work.

 

[frankanthony]

Wow removing the shim wasn't nearly as bad as it sounded I just pull the car onto ramps and used a transmission jack to lower the subframe... pretty simple... just difficult holding the clutch in place without a "spanner" wrench... all good with the ac now though! I haven't caught the clutch disengaging at all and the AC is nice and cold.. Thank you very much for that tip!

On the other hand the idle issue is still present and to be honest it almost feels like a slight miss now that you mentioned it... IACV is brand new, tps wiring is mint, I cleaned (sprayed) the mass air with electrical cleaner recommended in another post, and I checked everyone I could think of for a vacuum leak(it is much easier to look for vacuum leaks with the subframe dropped btw) but in the end I came up empty... Just before I came in today I had to reprogram the remote key fob (battery change) and while doing that I realized that the check engine light bulb does not illuminate, I believe it is supposed to for a few seconds at ign on.. so it is possible that the bulb is bad... I will look into that tomorrow and pull the present codes(if any) and post back with results. Thank you for your help!

 

[frankanthony]

I just replaced the check engine light bulb and sure enough 2 codes are present..

P1131 - Lack of heated oxygen sensor (Bank 1 Sensor 1) Switch Indicates Lean ... P0171 - Bank 1 System too lean...

Also I remembered seeing a post on here that said if you unplug the IACV and the car does NOT shut off within 5 seconds then you have a vacuum leak.. I did this test today and the car does NOT shut off, it just majorly revs down.

Does anyone have any experience or advice with this issue?

 

[SHOZ123]

Make sure the large vacuum hose on the back of the intake is good. It will rot off at the surge tank. This is for purging the vapor canister in the back.

 

[frankanthony]

Alright so I finally had a chance to do some more investigating... I found 2 minor vacuum leaks this morning when going over it with a fine tooth comb and removing the windshield wiper motor and plastics for more room. There is a little L shaped boot on the small black hose that plugs into the S spot on the plastic thing on the top of the drivers side firewall and the L shaped boot from the small red hose that plugs into the top of the intake. Both of these boots had cracks... I replaced them today and the car still will not shut off when I unplug the IACV. I also occasionally have acceleration issues when I drive the car along with the idling issues.

The large vacuum hose doesn't seem to be leaking, although the exterior is slightly rotted.

I am not even sure where else to look for leaks as I no longer hear any hissing even with the garden hose trick.

 

[three50one]

Unplugging your MAF sensor do anything?

 

[frankanthony]

I have only tried cleaning it not Unplugging it, I will try that later today. Thanks.

 

[frankanthony]

Okay I am back.. I replaced the large hose the runs to the passenger side since it was partially rotted and also replaced all of the tee lines, boots, and connectors I could find at advance auto. I still experienced no difference and unplugging the IACV still did not shut off the car.

When I unplug the MAF sensor the car actually runs a lot better... I experience no idle issues... it just seems like it shifts a little harder, although I may have been hyper sensitive to issues at the time.

As soon as I plug the MAF sensor back in the idle issues immediately start back up... I have tried a different MAF sensor (from parts 96 sho with 70k) in light of discovering this and it made no difference.

The only other thing I have noticed that was odd lately is that when idling I sometimes smell a little bit of a fuel smell.


Thanks for all of the help so far guys!

 

[three50one]

http://v8sho.com/SHO/AllSHOandNoGo.htm

Maybe? It could be a few things, but it's a known problem. Swap #8 coil with a different one and see if it gets better.

I mean you don't have a stalling issue, but it's worth a shot. Thus why a maybe.