Cold start problems - bouncing idle...

Andrews24

Active Member
Mar 13, 2021
67
29
28
36
Sylvania, OH
I kinda hijacked a really old thread earlier so I'll start my own. Here is what is going on...


Hey jrichker... I’ve used a ton of your advice over the years (back in the day your cranks but no start checklist was a life saver).

Ok, here’s my thing and forgive me if this is a dumb question... but I have had the cold idle problem since purchasing the car 2005 (under my ownership it sat for many years at one point and not many miles have been put on under my ownership, maybe 5,000). Once warm no issues (except for a hanging idle in deceleration until stopped). Anyway, something I’ve always wondered reading the numerous surging idle threads is, does this pertain to a car that is heavily modded and needs a tune (which is what I feel I need - or is this still the process needed to be done in the garage)? I’m pretty knowledgeable but honestly not sure on this. I’ve got a 230/230 duration .544/.544 lift cam, Windsor SR heads, Cobra upper/lower, 24 lb injectors & Pro M MAF, Long Tubes, etc etc. The car was built (in 2003) before I bought it. I rebuilt it in 2014 replacing the B cam with the Comp 276, lifters, Rockers, pushrods and springs (with a higher seat pressure). So nothing I did was a drastic change (just a slightly bigger cam) but anyway, the *issues* didn’t get worse after I went thru the motor in 2014... just giving you as much info as possible.

Mine starts and shoots to just say 2500 and sits for 2 seconds, then wants to die/500-600 rpm which is crazy low, then repeat

I’m 4 months into my winter project of 5 lug conversion, complete suspension replacement, underbody restoration, and tonight I fired the car up for first time since last year and the issue was worse than usual. 60 seconds of that and I was kinda scared. But my main question is when does one do these at home tests/settings of tps, etc, vs have it tuned? After all these years of ownership I’d like to fix this idle... I’m not looking for a dyno sheet and ‘oh I make xxx horsepower’ (in fact I’m scared it’ll break on the dyno lol), but I’ve always been under the impression (and told by some) it needs a tune... so, do I just drop it off and wah-la I’m done or do I do the checklist?

Thank you VERY much
 
  • Sponsors(?)


Andrews24

Active Member
Mar 13, 2021
67
29
28
36
Sylvania, OH
I just pulled codes with key on engine off, got the immediate 2 quick flashes... then 6, 7, 8, 4 (repeat). So 67, 84 is my assumption..

Then I tried to fire up the car and it shot up to 3,300 rpms and over compensates and stalls (I’ll post a video)...

Then pulled codes KOEO again and it went 6, 7, 8, 7, 8, 4 (repeat)... so 67, 87, 84...
 

Andrews24

Active Member
Mar 13, 2021
67
29
28
36
Sylvania, OH
Did some research on code 84... looked at my car and took some pics. Any thoughts?
 

Attachments

  • 20210418_213335.jpg
    20210418_213335.jpg
    283.9 KB · Views: 47
  • 20210418_213343.jpg
    20210418_213343.jpg
    171.5 KB · Views: 36

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
20,321
6,891
203
polk county florida
Do the surging idle checklist, I doubt you need 'a tune' maybe a tuneup. Most times it's a vacuum leak, that's in the list.
Just don't assume anything, do it step by step.
 

Andrews24

Active Member
Mar 13, 2021
67
29
28
36
Sylvania, OH
Do the surging idle checklist, I doubt you need 'a tune' maybe a tuneup. Most times it's a vacuum leak, that's in the list.
Just don't assume anything, do it step by step.
Yeah, I’m in the midst of going thru the checklist. The thing is I’m not gonna continually start my car with it rocketing up near 3,500 RPMs immediately on start up. I assume the next steps for codes I need the engine running... but at the moment I don’t want to keep subjecting the engine to that start up.

Last night I ordered an EGR Vacuum Solenoid (based on my code 84) and went ahead and ordered an EGR Valve and EGR Position Sensor. Just now I pulled the (original) EGR off and there was no Gasket to the Throttle Body... do I need one, I see some have a screen...? When I pulled the Position Sensor from the EGR the tip of the Sensor looks almost burned with some crud on it.

What are your thoughts to the last two pics I posted of that junction coming from the EGR... 3 screws in there as ‘plugs’ (not my doing) and what appears to be a crack in the line from the EGR...
 

7991LXnSHO

wanna catch the space herp
10 Year Member
Sep 1, 2010
5,398
1,741
194
Kearney, NE
The hard, colorful vac lines are getting brittle. Does anyone know if there is a repro assembly available or at least the hard line sections? I patched my car’s lines together to make everything functional again.
Those screws say something has been eliminated. Are the tad & tab solenoids still hooked up? I also wonder if the EGR is still getting proper vacuum.
 

Andrews24

Active Member
Mar 13, 2021
67
29
28
36
Sylvania, OH
The hard, colorful vac lines are getting brittle. Does anyone know if there is a repro assembly available or at least the hard line sections? I patched my car’s lines together to make everything functional again.
Those screws say something has been eliminated. Are the tad & tab solenoids still hooked up? I also wonder if the EGR is still getting proper vacuum.
The tab and tad are below the egr vacuum regulator solenoid correct? If so, yes they are connected

EDIT... I’m still learning the vacuum side of things... the TAB & TAD are there and connected like I said, but I would have to double check to see exactly how. For example, my canister is there but not hooked up (except for the line up to the Upper Intake by the Throttle Body) and smog has been removed, etc

Yeah regarding the EGR... in my hand I push that rod in then cap the hole the line would go into with my thumb, and that rod releases a little... my understanding is it shouldn’t move AT ALL...? Also, with that hole capped I can still push the rod (obviously it’s much harder but I can still push). And my thumb caps that hole for the EGR hose, I’m 100% sure I’m fully blocking it
 
Last edited:

Andrews24

Active Member
Mar 13, 2021
67
29
28
36
Sylvania, OH
I went ahead and replaced the EGR, EGR position sensor, and EGR solenoid - measured the 5V on one wire on the Position Sensor and something like .024 on the other (the checklist says one is supposed to measure approximately .6-.85), I didn’t have a code 31 tho like the checklist suggests one may - and these tests were all done with KOEO because as I’ve said the start up is very *high*, quickly, and I don’t want to keep subjecting the motor to that. Over at the EVR (solenoid), I got the correct voltage (13.3) on the one line...

So those new parts didn’t fix it and the voltmeter tests are showing wiring is fine. And remember the problem is only when motor is cold. I’m starting to think it’s the IAC (even tho I have replaced it during my ownership, and it is very clean inside) or the MAF... it’s an (old) Pro Flow, PFT-77. Any suggestions on things I can test without it running (watch the above video if you haven’t, to see why I’m not a huge fan of continuing to try to start it)
 
Last edited: