Replaced Drivers side injectors chasing a popping issue. Seemed to run fine on first trip.

Currently can't get idle lower than 1k with IAC disconnected and idle screw backed out where TB blades are closed. Randomly(idle or driving) the IAC seems to open up on its own(loud hissing sound) and runs like crap and AF goes up over 20:1, then seems to clear up and run fine.

Replaced fuel pump, IAC, TPS, put in an older tune no difference..

Feel like I have a vacuum leak because of the high idle, but why would the IAC open to let in more air and compound the problem?

Any thoughts...... ZZ4, Accel, Super Ram in a Sand Car

 

100 views....Nothin?

 

Well, replacing half your injectors is a weird thing to do and messing with the idle screw is treading down the path of darkness. Get a datalog when it's acting up. See if you can get it to idle up with some propane or use a smoke machine to find vacuum leaks. Verify IAC and TPS are calibrated correctly. Check grounds, look for burnt wires. Check fuel pressure.

 

Thanks for reply.
*All injectors used were recently serviced and same Accel injectors as what's in there currently. Popping was drivers side only(did not resolve issue). Felt no need to replace all.
*Adjusting idle is no big deal. Key on, disconnect IAC, key off. Start and set idle with set screw to 450rpm. Key off, plug in IAC, Done.
*Adjust TPS to .54v
*All wires are intact and grounded
*Fuel pump was replaced, Pressure set to 43.5psi
- Since the Accel gen 7 ECU has no ALDL, I'm not sure as to connecting A&B pins to enter a diagnostic mode. I assume the IAC parks itself closed when key turned on.
- I have a smoke machine to check for leak and will connect to laptop next time I'm at out with car.
- Since I closed the throttle blade and still had a 1k idle. Would it be accurate to assume a vacuum leak?

 

I know nothin about the Accel gen 7 but if it's anything like certain oem ECMs, key on engine off retracts it to "145" with "160" being fully opened. You want it completely closed off which is "0" to adjust the minimum idle. On the oems, it's jump A&B, key on engine off wait 30 seconds, disconnect IAC connector, key off, remove A&B jumper, start engine then adjust minimum idle. Reconnect IAC connector when done. hth

 

That would be a part of IAC setting i'm unsure of. There is no A-B pins to jump as the ECM is different, Perhaps there is a specific way to set the IAC that I am unaware of.
Maybe an Accel expert can chime in.

 

I had been chasing high revs for many years, no amount of tuning could fix the issue. The IAC did what it wanted to.

I simply blocked off the passage to my IAC, adjusted my throttle blades to where I wanted it. This solved all my idling and cold start problems. I just add more fuel for the cold starts. My car runs in open loop only, so this may not work for your setup. Ya might give it a try, and see if you like the results. If not, you can just remove the gasket and go back to the previous tune.

Again, I have a large cam and this completely worked for me. I wish I had done it ten years ago.

However, I'm not saying this is the fix for everyone.

 

That is an option. However, the car idled fine prior to removing the intake plenum to replace injectors. I would prefer to fix the problem if possible, before taking the IAC out of the Loop.

 

Then yes, I would suspect it's directly related to the injectors or a vacuum leak.

 

Heat Seeker, what table did you use to add fuel at cold start, and how much?

 

I believe it's Open Loop% of Change vs Coolant Temp. I'll have to look on my tuning laptop to see how much.

 

Okay, just took a look at it. it's Open Loop AFR Ratio % Change vs Coolant Temp.

Here's what I have:

Deg ----- % Change to

-40 thru 68 ---- 25.00 %
90 ----- 19.92%
111----- 16.02%
133 -----12.50%
154 thru 306 ----- 8.98%

 

Thanks, Should have no problem converting % change to use in my Accel program.

 

Are you using the stock throttle body?

If so maybe one of the top or bottom gaskets are leaking / got damaged. I had idle problems for YEARS and no matter what i did the stupid thing kept idling high at 1500.

It looked fine, and i heard or saw no leaks from the throttle body which I've had on and off several times already.......but I recently disassembled the whole throttle body, replaced the top plate gasket and IAC housing gasket and cleaned the IAC port vigorously... its now idiling normally. I used standard motors gasket set 2009

My guess is that the P/O installed that air foil thing in the throttle body which requires removing the top pate and he never resealed it properly or something. Never saw any smoke leaks though. its possible maybe your gasket got damaged or dislodged?

 

I've had car for 10+ years. Never had the Accel TB off intake or plates. Cleaned IAC port several times. hopefully If there is a leak, I'll find it next week with my smoke macheene.

 

Just got back from the dunes. Turned out to be a failing computer. I swapped out a backup I had as a last resort, a everything went away.