Looking for input!!! - SRT Forums

blubyu · 07-01-2008, 09:18 PM

I'm running a DCR stage 3 with stock wheel.Stage 3 rail,stage 2 injectors,walboro 255lph pump.Car runs
great with sct flash but i have a strange problem.
At cruise speeds say 70mph if i climb a long hill.
Say a half mile or longer my car frequently starts
to dump extra fuel causing afr to go from 14.7 to
the 11.5 to 12 range.AFR's will stay in that range
untill i turn the car off and restart it.

Any ideas?

Nick Chestnut · 07-02-2008, 08:38 AM

Quote: Originally Posted by blubyu

I'm running a DCR stage 3 with stock wheel.Stage 3 rail,stage 2 injectors,walboro 255lph pump.Car runs
great with sct flash but i have a strange problem.
At cruise speeds say 70mph if i climb a long hill.
Say a half mile or longer my car frequently starts
to dump extra fuel causing afr to go from 14.7 to
the 11.5 to 12 range.AFR's will stay in that range
untill i turn the car off and restart it.

Any ideas?

I used to have this problem before SCT. It appears to have gone away since I started tuning with SCT. I never did figure out what caused it or why.

Is it somewhat random or will it occur consistently? Do you happen to have the ability to datalog any OBD-II data?

04blusrt_4 · 07-02-2008, 09:12 AM

Quote: Originally Posted by blubyu

I'm running a DCR stage 3 with stock wheel.Stage 3 rail,stage 2 injectors,walboro 255lph pump.Car runs
great with sct flash but i have a strange problem.
At cruise speeds say 70mph if i climb a long hill.
Say a half mile or longer my car frequently starts
to dump extra fuel causing afr to go from 14.7 to
the 11.5 to 12 range.AFR's will stay in that range
untill i turn the car off and restart it.

Any ideas?

Sounds like the car is going under some sort of load, and so is possibly entering boost. If the MAP sensor picks this up, it should start to richen you up a little, how much will depend on how it is reading the map.

What MAP/TIP sensors are you running? What base map file do you have in the SCT?

duster360 · 07-02-2008, 09:51 AM

Quote: Originally Posted by blubyu

AFR's will stay in that range
untill i turn the car off and restart it.

Overly rich with a small load increase can be explained by just a bad tune. Whats more of a concern is why the F/A stays f'ed up until you turn the car back on.

Something else is going on. Its as if the ecu is stuck in open loop or the ecu is getting bad info im thinking. High TPS voltage is my first guess. Depends how how jacked up the flash is.

04blusrt_4 · 07-02-2008, 10:01 AM

kind of also sounds like limp mode enabled...

duster360 · 07-02-2008, 11:06 AM

Quote: Originally Posted by 04blusrt_4

kind of also sounds like limp mode enabled...

fyi there's no such thing as "limp mode"

e_freeman85 · 07-02-2008, 12:43 PM

whats odd is i have seen blus tune first hand and theres nothing wrong with it. its not a bad tune but its also by far not a great one the only difference between his and my tune is the amount of timing and fuel and no fuel has been adjusted before 15psi or so. the only redflag i saw was the D0011 setting was odd mine hasnt been adjusted and its 45 his hasnt either and its 179
i was wondering if this super richening could be caused by stg3 fuel rail and 255 pump its hooked up to a boost source but hes working off a stage2 tune with no rising rate settings on the pcm
i hope this info helps in finding the problem causeing this

sour kraut · 07-02-2008, 01:03 PM

I would datalog the TPS voltage, and the upstream o2 while climbing the hills. This could give us more info.

04blusrt_4 · 07-02-2008, 02:07 PM

Quote: Originally Posted by duster360

fyi there's no such thing as "limp mode"

What happens when cat temps get too high, and comp pulls timing?

duster360 · 07-03-2008, 07:40 AM

Quote: Originally Posted by 04blusrt_4

What happens when cat temps get too high, and comp pulls timing?

I don't think you understand what a "limp mode" actually is. Those are independant responses by the ecu to specific monitored conditions or sensor inputs. No different than the ecu spraying more fuel when you step on the gas pedal than at idle. When the cat temp reduces so does the timing adjustment. Cat temp is just one of the many modifiers to timing, no different really than Knock counts, Air temp, psi or RPM.

A true "limp mode" would ignore nearly all outside inputs and deliver a predetermined and often limited performance until manually reset. A limp mode on a SRT would deliver almost no boost and very little fuel to limit engine load and probably vehical speed to around 30mph. Just enough to get you to a shop or off the interstate. Does this sound familiar? Didn't think so.

like I said
"SRT ecu's have no such "limp mode"

duster360 · 07-03-2008, 07:48 AM

Quote: Originally Posted by sour kraut

I would datalog the TPS voltage, and the upstream o2 while climbing the hills. This could give us more info.

ditto

JANNETTYRACING · 07-05-2008, 07:13 AM

Quote: Originally Posted by blubyu

I'm running a DCR stage 3 with stock wheel.Stage 3 rail,stage 2 injectors,walboro 255lph pump.Car runs
great with sct flash but i have a strange problem.
At cruise speeds say 70mph if i climb a long hill.
Say a half mile or longer my car frequently starts
to dump extra fuel causing afr to go from 14.7 to
the 11.5 to 12 range.AFR's will stay in that range
untill i turn the car off and restart it.

Any ideas?

There are several Fuel adders, Cat over temp would be my first choice, when your under load for longer than a minute the computer adds fuel to protect the cat converters and can go as rich as 9.0:1 and stay there till the cat cools down.

I can reproduce those condition on my Chassis Dyno as I have Eddy Current Load Motors, and monitor Cat temp.

There are also Fuel adders for Knock, this would be my second choice, the longer you are under load the more chance of knock so again the computer adds fuel to suppress knock also as rich as 9.0:1

For these there are timers that have to run out before normal A/F is resumed.

All Computers have a LIMP MODE, and there is a possibility your entering it, if in fact you have to power down to get back to normal A/F.

FYI I have put several SRT4s in Limp mode, in fact there are several levels of limp mode 6 that I know of, and he may be just entering level 1.

Sorry Duster, I will have to disagree with you on this one.

Ted.

JANNETTYRACING · 07-05-2008, 07:16 AM

Quote: Originally Posted by 04blusrt_4

What happens when cat temps get too high, and comp pulls timing?

The computer does not pull timing for Cat overtemp, it simply adds fuel to cool, how much fuel is EGT dependant.

Reducing Timing would increase Cat Temps.

Ted.

e_freeman85 · 07-05-2008, 09:12 AM

the chances for knock are fairly low it could be the problem but his tune is extremley conservitive so the knock would have to be from a freak perameter causeing it
but i could be wrong

duster360 · 07-06-2008, 08:20 AM

Quote: Originally Posted by JANNETTYRACING

All Computers have a LIMP MODE.....
FYI I have put several SRT4s in Limp mode, in fact there are several levels of limp mode 6 that I know of, and he may be just entering level 1.

Sorry Duster, I will have to disagree with you on this one.

Ted.

It seems you also disagree with the Chrysler calibration engineers too, then. I have yet to see a reference to or even an acknowledgment of an engine "Limp mode" in any Chrysler engine diagnostic manual or technician training regime. (At least since mid 1980's when the first tbi came out.)

Please explain these "levels" of Limp Modes in detail.