Stalling
- Thread starter Nomar
- Start date
As above , check spark at the coil , may indicate a bad amp or coil. fuel pressure at the rail ? hols old is your fuel pump ? they seem to fail around 120 k ..good luck.
Dang!
In the past week, I put in a new fuel pump/filter.
Swapped dizzy from a good running truck(with the amp)...
Swapped MAF's from good running truck....
Swapped in 2 other 14CUXs and a 4.2 14CUX...
Swapped coolant sensor from good running truck...
The stalling seems better but there is no power and it seems like the truck hiccups; sorta like a backfire but no pop.
I could find no leaks around the intake with ether but it doesnt seem to be pulling much vacuum either...
Why is this truck running so poorly???
Will a Discovery fuel rail fit a 3.9 RR?? I have one in the shed...
In contrast to more modern engine management systems, the 14CUX controls fuel delivery only; it does not control spark ignition. On 14CUX-equipped vehicles, the spark control is done mechanically with the use of a distributor.
When the ignition is first turned on, the ECU energizes a relay that runs the fuel pump for a short time to pressurize the fuel rail. Once the starter motor begins to turn the engine, the ECU gets a 12VDC signal that causes it to run the fuel pump again, and energize the fuel injectors. For the next several seconds, the injector pulse width is wider than normal to provide sufficient fuel for starting. Idle control is performed by adjusting a stepper-motor-driven bypass valve in the intake plenum. When the ignition is switched off, the ECU winds the bypass valve fully open to provide enough air the next time the engine is started.
To determine the amount of fuel required by the engine, the ECU reads a number of sensors measuring the following factors:
* Intake air mass
* Coolant temperature
* Engine speed
* Throttle position
* Fuel temperature
* Exhaust oxygen content (narrowband)
* Road speed
The intake air mass is measured with a "hot-wire" mass airflow sensor: drawn in by intake manifold vacuum, air moves past an electrically-heated wire filament, and the degree to which the filament is cooled indicates the mass of the airstream.
Two factors (crankshaft speed and engine load) are used to index into a two-dimensional matrix of numeric values known as the "fuel map". The value read from the map is offset by other environmental factors (such as coolant temperature). This corrected value is then used to meter fuel by pulse-width modulating the fuel injectors. Because each bank of the V8 feeds an exhaust line with its own oxygen sensor, the air/fuel ratio can be monitored and controlled for the banks independently.
The 14CUX PROM may contain up to five fuel maps, which allowed a single ROM image to contain maps for multiple target markets. In some markets, the active map is selectable by placing an external tune resistor on a particular pin of the ECU. This external map selection was disabled in the code for North American specification (NAS) vehicles.
Also from BritishV8...
Road Speed Transducer (photo not yet available)
On Range Rovers, the Road Speed Transducer is mounted on a bracket on the left hand frame rail adjacent to the motor mount. The transducer provides road speed data to the ECU (and on Range Rovers it's also needed by the speedometer). Based on input from the Road Speed Transducer, the ECU selects an appropriate fuel map. When the Road Speed Transducer is omitted or inoperable, the ECU never leaves "idle mode". It isn't clear from the Rover literature we've found exactly how many other modes the ECU might enter if it had an operational Road Speed Transducer. You can actually drive in idle mode, especially if you manually re-adjust idle speed at the MAF Sensor, but cruise fuel economy should be better with a Road Speed Transducer signal properly reaching the ECU.
For safety reasons, Range Rovers have a "kill-joy" function built into the ECU program. If the Road Speed Transducer provides too fast a signal, the vehicle will stop accelerating.
Our example system didn't come to us with a Road Speed Transducer, but we'd like to have one so we can analyze how it functions and determine how feasible it is to provide a road speed signal to the ECU from another source. (For example, anyone who fits an aftermarket electronic speedometer also fits an aftermarket speed transducer. We don't know if an aftermarket speedometer sender can be used for the fuel injection system also.)
I did not think the RST had input to the ECU but this says differently.
One more part to try swapping.
In the past week, I put in a new fuel pump/filter.
Swapped dizzy from a good running truck(with the amp)...
Swapped MAF's from good running truck....
Swapped in 2 other 14CUXs and a 4.2 14CUX...
Swapped coolant sensor from good running truck...
The stalling seems better but there is no power and it seems like the truck hiccups; sorta like a backfire but no pop.
I could find no leaks around the intake with ether but it doesnt seem to be pulling much vacuum either...
Why is this truck running so poorly???
Will a Discovery fuel rail fit a 3.9 RR?? I have one in the shed...
In contrast to more modern engine management systems, the 14CUX controls fuel delivery only; it does not control spark ignition. On 14CUX-equipped vehicles, the spark control is done mechanically with the use of a distributor.
When the ignition is first turned on, the ECU energizes a relay that runs the fuel pump for a short time to pressurize the fuel rail. Once the starter motor begins to turn the engine, the ECU gets a 12VDC signal that causes it to run the fuel pump again, and energize the fuel injectors. For the next several seconds, the injector pulse width is wider than normal to provide sufficient fuel for starting. Idle control is performed by adjusting a stepper-motor-driven bypass valve in the intake plenum. When the ignition is switched off, the ECU winds the bypass valve fully open to provide enough air the next time the engine is started.
To determine the amount of fuel required by the engine, the ECU reads a number of sensors measuring the following factors:
* Intake air mass
* Coolant temperature
* Engine speed
* Throttle position
* Fuel temperature
* Exhaust oxygen content (narrowband)
* Road speed
The intake air mass is measured with a "hot-wire" mass airflow sensor: drawn in by intake manifold vacuum, air moves past an electrically-heated wire filament, and the degree to which the filament is cooled indicates the mass of the airstream.
Two factors (crankshaft speed and engine load) are used to index into a two-dimensional matrix of numeric values known as the "fuel map". The value read from the map is offset by other environmental factors (such as coolant temperature). This corrected value is then used to meter fuel by pulse-width modulating the fuel injectors. Because each bank of the V8 feeds an exhaust line with its own oxygen sensor, the air/fuel ratio can be monitored and controlled for the banks independently.
The 14CUX PROM may contain up to five fuel maps, which allowed a single ROM image to contain maps for multiple target markets. In some markets, the active map is selectable by placing an external tune resistor on a particular pin of the ECU. This external map selection was disabled in the code for North American specification (NAS) vehicles.
Also from BritishV8...
Road Speed Transducer (photo not yet available)
On Range Rovers, the Road Speed Transducer is mounted on a bracket on the left hand frame rail adjacent to the motor mount. The transducer provides road speed data to the ECU (and on Range Rovers it's also needed by the speedometer). Based on input from the Road Speed Transducer, the ECU selects an appropriate fuel map. When the Road Speed Transducer is omitted or inoperable, the ECU never leaves "idle mode". It isn't clear from the Rover literature we've found exactly how many other modes the ECU might enter if it had an operational Road Speed Transducer. You can actually drive in idle mode, especially if you manually re-adjust idle speed at the MAF Sensor, but cruise fuel economy should be better with a Road Speed Transducer signal properly reaching the ECU.
For safety reasons, Range Rovers have a "kill-joy" function built into the ECU program. If the Road Speed Transducer provides too fast a signal, the vehicle will stop accelerating.
Our example system didn't come to us with a Road Speed Transducer, but we'd like to have one so we can analyze how it functions and determine how feasible it is to provide a road speed signal to the ECU from another source. (For example, anyone who fits an aftermarket electronic speedometer also fits an aftermarket speed transducer. We don't know if an aftermarket speedometer sender can be used for the fuel injection system also.)
I did not think the RST had input to the ECU but this says differently.
One more part to try swapping.
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A buddy of mine went through 2 or 3 amplifiers in a few weeks time on a 1990 RRC before he "converted" it to an MSD ignition. One of the amps was on a new distributor. He also threw a couple if different coils at it. Sad thing is that the ignition components almost always passed all of the tests listed in the service manual.
After rigging up the MSD box instead of the amp, (it was cheaper than a relocation kit) all of the problems with stalling went away.
I'm not sure if the amps where just cheap, or something special was killing them.
After rigging up the MSD box instead of the amp, (it was cheaper than a relocation kit) all of the problems with stalling went away.
I'm not sure if the amps where just cheap, or something special was killing them.
Well, I think I can safely rule out the amplifier because I swapped distributors from the good running '91 to the '91 Hunter.
The previously good running truck still runs great with the dizzy from the bad running truck.
The stalling issue seems to be gone but there is just no power in the bad truck.
Rechecked timing just to make sure.
The previously good running truck still runs great with the dizzy from the bad running truck.
The stalling issue seems to be gone but there is just no power in the bad truck.
Rechecked timing just to make sure.
Yeah, I agree. I missed the part about swapping them.
This is why I hate Lucas and GEMS... neither one will reliably throw a code and tell you that something is wrong. I'll stick with my D2's that everyone seems to hate
Could it be a restriction in the cats? My D1 had a bad cat and was gutless. Eventually it got to the point where it wouldn't rev over 2000.
This is why I hate Lucas and GEMS... neither one will reliably throw a code and tell you that something is wrong. I'll stick with my D2's that everyone seems to hate
Could it be a restriction in the cats? My D1 had a bad cat and was gutless. Eventually it got to the point where it wouldn't rev over 2000.
jafir said:Yeah, I agree. I missed the part about swapping them.
This is why I hate Lucas and GEMS... neither one will reliably throw a code and tell you that something is wrong. I'll stick with my D2's that everyone seems to hate
Could it be a restriction in the cats? My D1 had a bad cat and was gutless. Eventually it got to the point where it wouldn't rev over 2000.
Oh yeah, these cats were gutted.
Another good point though.
If it is back firing through the intake or popping here I would suspect timing chain based on personal experience. I assume youve checked fuel pressure even with the new parts. My RRC seems low on power also, I am not sure if it is due to cam issues or a weak spark.
Well it requires you to pull the timing cover to check that the marks on the crank gear and cam gear are lining up correctly.
From your cylinder pressure test they look a bit low from my experience.
HOWEVER, before I pulled the timing cover that there's a lot of other things I'd check.
I assume you've ruled out the obvious things like clogged air filter, incorrect ignition timing, stepper motor, TPS, etc.
You mentioned the cats were gutted-was all the material removed? Or could a piece have fallen down and partially blocked the exhaust? Try getting under and shaking the cats to hear if there's a rattle.
Frankly I think these trucks run better with proper cats and a little back pressure that the cats provide.
You replaced the fuel pump and filter-are you getting good pressure at the injectors?
From your cylinder pressure test they look a bit low from my experience.
HOWEVER, before I pulled the timing cover that there's a lot of other things I'd check.
I assume you've ruled out the obvious things like clogged air filter, incorrect ignition timing, stepper motor, TPS, etc.
You mentioned the cats were gutted-was all the material removed? Or could a piece have fallen down and partially blocked the exhaust? Try getting under and shaking the cats to hear if there's a rattle.
Frankly I think these trucks run better with proper cats and a little back pressure that the cats provide.
You replaced the fuel pump and filter-are you getting good pressure at the injectors?
GregH said:
Air filter is good; checked and rechecked timing; swapped TPS's with the good truck; stepper motor...didnt swap that but I could....hell, I'd change tail light bulbs if I thought it would help at this point!
Yeah, I gutted these with the y-pipe off the truck; cut windows in each cat and chopped and shopvacced all the bits= clean as a pin pipes.GregH said:
GregH said:
Well, I dont know. The dang RR Classics have no valve on the rail!
Does anyone know if a Disco I fuel rail will fit a RRC??? I've got one with good injectors on it...
I will pull the pump out of the LWB and give that a try, too. That truck hauls ass...
Thanks for your input Greg, it's helping me to go through my mental checklist again.
az_max said:
LOL
Yeah someone did ask this before! Sounds like A Disco fuel rail will fit, according to Bruce Grinnel.
Thanks max!
At the rear of the fuel rail is a pressure regulator, any chance this could fail and restrict fuel flow?
Also, from the WSM...
"The road speed transducer provides road speed data to the ECU. The ECU in turn detects vehicle movement from the road speed input and ensures that idle speed control mode is disengaged. Should the transducer fail in service the ECU idle speed control would become erratic."
It doesn't say anything about running erraticly at road speed??
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ptschram
Well-known member
W/R/T fuel rail, yes and no.
Depending upon the year, the return line/pressure regulator was different, but they can be easily made to fit.
I told you to check fuel pressure, didn't I. I also told you to disconnect the speed sensor as well...
Good thing you sent candy for Christmas (God, I hope it was Jeff-somebody sent me candy for Christmas)
Depending upon the year, the return line/pressure regulator was different, but they can be easily made to fit.
I told you to check fuel pressure, didn't I. I also told you to disconnect the speed sensor as well...
Good thing you sent candy for Christmas
(God, I hope it was Jeff-somebody sent me candy for Christmas)ptschram said:W/R/T fuel rail, yes and no.
Depending upon the year, the return line/pressure regulator was different, but they can be easily made to fit.
I told you to check fuel pressure, didn't I. I also told you to disconnect the speed sensor as well...
Good thing you sent candy for Christmas
Hey, that candy was for the shop cat!
PT, you know I can't check fuel pressure at the rail.
Is it worth checking pressure at the filter?
That wouldn't tell me if gas is making it all the way to the manifold.
I'll swap the speed sensors and report back although the manual tells me this won't have an effect.
ptschram
Well-known member
Nomar said:Hey, that candy was for the shop cat!
PT, you know I can't check fuel pressure at the rail.
Is it worth checking pressure at the filter?
That wouldn't tell me if gas is making it all the way to the manifold.
I'll swap the speed sensors and report back although the manual tells me this won't have an effect.
Shop cats don't need no stinkin' candy! They can get meeses if they're hungry!
For the love of God, buy a pair of 5/16" hose barbs and a tee to mate with them and a pressure gauge that mates with the tee. Cut the fuel line, insert tee, measure fuel pressure. Bask in the glow of KNOWING if fuel pressure is a problem.
Think outside of the (cat) box! You can probably get most everything you need at Home Depot or similar. While you're at it, get a "hose mender" made out of brass so you can remove the tee.
You don't need a fancy one that costs $100, but I will say that when I needed one last week, it was UBER handy. I know my 88 will run on 15-17 PSI, not well, but runs