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newbie with idle problem

Hi everyone, I'm Justin. Holy first post Batman! So here's the deal. I just installed a keydiver ecu and a set of 780cc injectors. I had a smooth running car before I did this, and now the idle surges between 1300 and 1700 rpm. I know that the throttle open/closed switch is good, and I swapped the isc motor with one that I don't know if it is good or not, but that didn't help anything. Does anyone have a suggestion? Thanks y'all.
 
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Wait a minute.....your car ran smooth before keydiver ecu work and chip? /ubbthreads/images/graemlins/dunno.gif /ubbthreads/images/graemlins/shocked.gif
 

I'm sure there must be another underlieing issue. Keydiver doesn't have a rep like he does, f***ing peoples sh*t up. I check stuff out before pointing fingers, common sense tells me. It's not a common complaint, for sure
 

1qkfwd

Well-known member
Joined
Sep 29, 2009
Messages
209
Location
Sun Valley, NV
Umm doesn't really sound like he was blaming keydiver for the issue, he was just saying it was fine til he changed the chip.

Did you order the chip? If you asked for a different idle on the chip then you need to set the idle screw to match the new rpm of what the ecu targets. If it's outta range it will surge.
 

I'm certainly not trying to blame keydiver. I know three other cars running his stuff and they run really well. I was just looking for suggestion on where to start my diagnosis. The only changes that I requested be made on the chip were 8k redline, injector size, stutterbox, nlts, octane compensation, fuel cut elim.
 

1qkfwd

Well-known member
Joined
Sep 29, 2009
Messages
209
Location
Sun Valley, NV
The only thing I can suggest is boost leak test the car, then go through all the basics. Did you install the bigger injectors with the chip? Maybe there's a leak somewhere. Injector o-ring maybe.
 

The O-ring would make more sense than the boost leak IMO. He stated the car was running smooth until the ECU work and injectors. If he does have a boost leak it must not of been that noticable performance wise.
Good news is, if it is O-rings, there relatively cheap.
 

1qkfwd

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Joined
Sep 29, 2009
Messages
209
Location
Sun Valley, NV
Maybe I shouldve rephrased that. The lower injector ring that goes into the intake manifold. It would cause a boost leak thus the surging idle.
 

AnotherNewb

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Apr 25, 2010
Messages
1,472
Location
Orlando, FL
"Injector insulator" Tried ordering lower "O RINGS" and went through 3 sets of orings before I could get the right set of INJECTOR INSULATORS
 

*update*
I have determined a couple things. The injector insulators are new, and I triple checked the installation of these and they are properly seated and the injectors are seated inside of these properly. I can't imagine that the chip is faulty, and since the injectors were purchased used, that is were I'm going to start. I'm assuming that they are larger than advertised, considering that way the car runs. It screams at higher rpms, but is sluggish (more than normal) off boost. In first gear it sometimes stutters when there is minimal throttle input. I think I'll look at finding a new set of densos.
 

He is running a rewired 255 pump with a stock FPR, so I'm thinking he has massive FPR overrun at idle, making him way too rich. So, I'm sending him a new chip with way less deadtime compensation, to lean out the idle.
 

Ok, update. I've installed a new chip and a new set of injectors. The injectors are brand new fic 750's purchased from keydiver himself (who is one helluva nice, cool guy). The idle is still hunting, and at around 4500 rpm the car stumbles and then takes off like a rocket. I've gone ahead and swapped in a 2g mas, although the chip isn't set up for it, and the stumble is now gone, but the poor idle persists. I have checked everything in the intake system for airleaks, short of removing the entire intake manifold. I'm stumped. Any suggestions are greatly appreciated.
 

AnotherNewb

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Joined
Apr 25, 2010
Messages
1,472
Location
Orlando, FL
The stumble is gone, but the idle serge still exists? Do you have a logger? That could tell you a lot about what is going on with your engine. Was the 2g MAS hacked when you installed it? i.e. honey combs removed, screw turned out. Get a multi meter and test out your ISC and be sure you have a good one on there, and since you have your meter out, check to make sure your TPS is properly set. Check your Temp sensor too, that can cause wierd idle problems too. What was the condition of your ECU before you sent it to key diver?
 

The ecu is entirely a keydiver piece. My old ecu is untouched and sitting in the garage. I do have a data logger, but I just got it and am still learning what all that info really means. The 2g mas is stock. Unhacked. Tps reads 5% at closed throttle and 98% at WOT. The coolant temp reads 95-100 degrees celcius at operating temp. Right now isc reads 0 on the datalogger but I don't know if that is full open or full closed.
 

The value on the datalogger that is labeled isc stays at 0 during idle, however there is a value labeled vspd that cycles between 0 and 85, but I don't what that value stands for.
 

stevep

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Joined
Oct 23, 2004
Messages
416
Location
St. Charles, IL USA
Quoting galant1517:
however there is a value labeled vspd that cycles between 0 and 85, but I don't what that value stands for.




Nothing, it's there for the add-on hardware the guy was going to build. Without that hardware it's just looking at some address in the ECU's memory.

If your ISC is stuck at 0 you need to check for anything that would let air bypass the throttle butterfly and try turning the BISS in a bit. Check the coils resistance on the ISC before digging too far into anything else.
 

I've got the BISS cranked shut, I've looked fifteen times for air leaks, can a pcv valve be the culprit? The reason I ask is that the other vent on the V/C is to atmosphere. Is there anywhere to get the ISC other than the dealer? They want $332 + tax. I am really confused about this whole situation because the car idled perfectly on my old ecu and 450's.
 

You can always put the old sh*t on and go from there then. /ubbthreads/images/graemlins/dunno.gif
 
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