ECU driving me to drink

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tasvalowna

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Hi , ive fitted a 5.7 and rfe545 from an 07 ram into a 1948 chrysler .Its completely stock and is running a hotwire harness and 05 ram ecu.
Ive been driving it since easter with varying issues.
The original ecu from hotwire runs perfectly but must have a dry joint or something as when it gets hot the car will not re start until it cools down then runs perfectly.
So i ordered another ecu from hotwire that would crank the car but nothing else.So returned that one which tested ok when he got it back?
I then spoke to B&G Chrysler and bought an 07 ECU which they re programmed to run stand alone. They sent me 2 because they werent sure if the first was going to work. They were right , neither of them run the car properly.1 runs good but the car goes into limp mode (no throttle response)when you go up a hill , the other has erratic rpm and will go into limp mode idle while testing it in the shed. Unfortunately these run on canbuss so my OBD scan tool wont read them through the hotwire harness.
I ordered another reco off ebay in sheer desperation but that one will not do anything but crank also.
where do I go from here?
Ive got 4 ecu's that all have different faults when you install them.........
can i use a diablosport thing to take the tune from the dry joint one and put it into the no go one?
Is there someone in the usa that can do this for me ?
Is there anyone that answers emails in the usa at all? (Im in australia)
Should i give up and spend a heap of cash to go aftermarket for a stock engine?
Im out of ideas , HELP !!!!!!!!!
 
If you've had that many issues with ECUs to me is seems more like the issue might be elsewhere. The chance of getting that many faulty ones in a row seems pretty unlikely. If it will crank and not start it could be a cam or crank sensor problem. Could have been flakey with the first ECU and then went out for the later ones you tried. When in doubt I'd check the wiring to those to be sure they are getting reference voltage and ground. When I first installed my MSD to run my ignition on my carb setup it wouldn't start brand new out of the box. Found out the ground wire had pushed back out of the connector and wasn't making good contact.

And even though those computers are CAN based, they should still send out OBDII codes you can read with a code reader if you have the port wired in. The cars the ECUs came out of had OBDII ports, so there's no reason they shouldn't still work. That could give you an idea if a sensor is throwing a code.
 
If you've had that many issues with (........) to me is seems more like the issue might be elsewhere.

THIS RIGHT HERE

OP:

What have you done to "determine" the ECU is actually the trouble?

Basics......Compression, spark and fuel...........

Does it have those things?
 
I was thinking the same thing. A possible ground fault. Can drive the system nuts. Different computers, slightly different ground paths.
Engine to body and chassis grounds are important.
 
Oh my money is on the ground fault also. I've traced MANY weird electrical gremlins to ground faults. Had a first gen Caravan that stalled on right hand turns..yup replaced the main ground wire to the battery,problem went away..
 
Oh my money is on the ground fault also. I've traced MANY weird electrical gremlins to ground faults. Had a first gen Caravan that stalled on right hand turns..yup replaced the main ground wire to the battery,problem went away..
Saw a battery do the exact same thing.
 
I hear what your saying and have done continuety tests on all the earth pinouts to my earth and all tested ok.
I have driven the car with 2 of the ecu's on 300 mile return trips , and with one if i drive under 60mph , it drives all day and night .With the other it will drive all day and night if I dont turn it off . All i do to swap between these in un plug one and slide the other in and plug that in . No other changes. If my wiring or sensors had issues , why would they both run but have completely un related problems ? I have swapped them back and forwards many times and the same faults stay with the same ECU's
 
If you've had that many issues with ECUs to me is seems more like the issue might be elsewhere. The chance of getting that many faulty ones in a row seems pretty unlikely. If it will crank and not start it could be a cam or crank sensor problem. Could have been flakey with the first ECU and then went out for the later ones you tried. When in doubt I'd check the wiring to those to be sure they are getting reference voltage and ground. When I first installed my MSD to run my ignition on my carb setup it wouldn't start brand new out of the box. Found out the ground wire had pushed back out of the connector and wasn't making good contact.

And even though those computers are CAN based, they should still send out OBDII codes you can read with a code reader if you have the port wired in. The cars the ECUs came out of had OBDII ports, so there's no reason they shouldn't still work. That could give you an idea if a sensor is throwing a code.

I though the OBD thing would be the same for both 05 &07 which is why i thought nothing of it when i ordered them . But then both the 2005 ones read ok and both the 2007 ones will not connect at all
 
I hear what your saying and have done continuety tests on all the earth pinouts to my earth and all tested ok.
I have driven the car with 2 of the ecu's on 300 mile return trips , and with one if i drive under 60mph , it drives all day and night .With the other it will drive all day and night if I dont turn it off . All i do to swap between these in un plug one and slide the other in and plug that in . No other changes. If my wiring or sensors had issues , why would they both run but have completely un related problems ? I have swapped them back and forwards many times and the same faults stay with the same ECU's

Continuity has nothing to due with a ground loop or noise interference, with complex electronic controls the OEMs take this into consideration when it is integrated into a vehicle. It costs nothing
to run a separate ground for the ECM.
 
Miss an engine to body ground on any old car and it will drive a person nuts.a buddy’s early 70’s grand prix melted two shift cables before we figured it out. Didnt know the history of the car,but discovered valve covers were removed and left strap hanging.
 
Random thoughts:

You buy these from a "reputable source?" Maybe they already had problems

Where are they mounted? Heat from engine?

Don't discount CONNECTOR PROBLEMS right there at the ECU
 
Random thoughts:

You buy these from a "reputable source?" Maybe they already had problems

Where are they mounted? Heat from engine?

Don't discount CONNECTOR PROBLEMS right there at the ECU

well thats an excellent question , who would you call a reputable source ?
Being an ozzy , I have no idea so let me know who is one!
Its mounted on the inner guard much where the factory ram one is located and ive been through the pins in the plugs over and over again because I had the same thought.

I will run an external earth from my earth point to the battery and see if that helps.
The earth lug is a big soldered on affair so I may even cut that off and solder another one on just to be sure they are all connected properly.
 
Earth to engine. Its sensor faults. Now, if you had access to a known good computer, or a truck that you could run your ecms in it may give you an idea whats goin on. Repeatedly throwing questionable parts at something and getting different results every time is an exercise in futility.
 
Earth to engine. Its sensor faults. Now, if you had access to a known good computer, or a truck that you could run your ecms in it may give you an idea whats goin on. Repeatedly throwing questionable parts at something and getting different results every time is an exercise in futility.
had close to same issue wont start or run hot my problem was bad maf sensor
 
Had a ford last winter that ran like poo. I had replaced a leaking p/s pressure sensor. Took forever to wrap my head around a junk in the box part, unplugged it and it ran perfect. Six hours later. Dtc came up as 5 volt reference fault.
Sometimes the simplest things cause the most grief.
 
well thats an excellent question , who would you call a reputable source ?

Well for example, did the ECUs come from a junkyard or other unknown such as private party sale and you had them flashed? Or did you buy them from someone who flashes them and 'stands behind' them?
 
I am not 100% certain but if I remember correctly there may be a couple of pinouts that changed between the 05 and 07 ecu's. This may be the reason you are having issues with the 07 ones. Tincup had some issues with his shutting down randomly or when hot. He may have some insight
 
Hi , ive fitted a 5.7 and rfe545 from an 07 ram into a 1948 chrysler .Its completely stock and is running a hotwire harness and 05 ram ecu.
Ive been driving it since easter with varying issues.
The original ecu from hotwire runs perfectly but must have a dry joint or something as when it gets hot the car will not re start until it cools down then runs perfectly.
So i ordered another ecu from hotwire that would crank the car but nothing else.So returned that one which tested ok when he got it back?
I then spoke to B&G Chrysler and bought an 07 ECU which they re programmed to run stand alone. They sent me 2 because they werent sure if the first was going to work. They were right , neither of them run the car properly.1 runs good but the car goes into limp mode (no throttle response)when you go up a hill , the other has erratic rpm and will go into limp mode idle while testing it in the shed. Unfortunately these run on canbuss so my OBD scan tool wont read them through the hotwire harness.
I ordered another reco off ebay in sheer desperation but that one will not do anything but crank also.
where do I go from here?
Ive got 4 ecu's that all have different faults when you install them.........
can i use a diablosport thing to take the tune from the dry joint one and put it into the no go one?
Is there someone in the usa that can do this for me ?
Is there anyone that answers emails in the usa at all? (Im in australia)
Should i give up and spend a heap of cash to go aftermarket for a stock engine?
Im out of ideas , HELP !!!!!!!!!
Very muc
Hi , ive fitted a 5.7 and rfe545 from an 07 ram into a 1948 chrysler .Its completely stock and is running a hotwire harness and 05 ram ecu.
Ive been driving it since easter with varying issues.
The original ecu from hotwire runs perfectly but must have a dry joint or something as when it gets hot the car will not re start until it cools down then runs perfectly.
So i ordered another ecu from hotwire that would crank the car but nothing else.So returned that one which tested ok when he got it back?
I then spoke to B&G Chrysler and bought an 07 ECU which they re programmed to run stand alone. They sent me 2 because they werent sure if the first was going to work. They were right , neither of them run the car properly.1 runs good but the car goes into limp mode (no throttle response)when you go up a hill , the other has erratic rpm and will go into limp mode idle while testing it in the shed. Unfortunately these run on canbuss so my OBD scan tool wont read them through the hotwire harness.
I ordered another reco off ebay in sheer desperation but that one will not do anything but crank also.
where do I go from here?
Ive got 4 ecu's that all have different faults when you install them.........
can i use a diablosport thing to take the tune from the dry joint one and put it into the no go one?
Is there someone in the usa that can do this for me ?
Is there anyone that answers emails in the usa at all? (Im in australia)
Should i give up and spend a heap of cash to go aftermarket for a stock engine?
Im out of ideas , HELP !!!!!!!!!
Very much the trouble associate with temperature. The 1st ecu seem fine, the problem could be weak fuel supply at hot temperature, or spark cut off because high temp changing sensor structure.

Do this. Put the 1st ecu back, drive it until hot. Turn off and start. When it won't run spray starting fluid through intake. If if run: the problem is fuel supply. If if won't run: no spark. At this step, check crankshaft and camshaft sensors. Possibly your engine temperature higher than factory expected operating temperature, that distort crank/cam sensors (or whatever sensor relate to ignition )

Only guessing like what I would do if I have the same car. I'm not familiar with 5.7 hemi.
 
Last edited:
Very muc

Very much the trouble associate with temperature. The 1st ecu seem fine, the problem could be weak fuel supply at hot temperature, or spark cut off because high temp changing sensor structure.

Do this. Put the 1st ecu back, drive it until hot. Turn off and start. When it won't run spray starting fluid through intake. If if run: the problem is fuel supply. If if won't run: no spark. At this step, check crankshaft and camshaft sensors. Possibly your engine temperature higher than factory expected operating temperature, that distort crank/cam sensors (or whatever sensor relate to ignition )

Only guessing like what I would do if I have the same car. I'm not familiar with 5.7 hemi.

when it wont start when its hot , its because the fuel pump circuit doesn't fire . Normally when the key is moved to the on position , the fuel pump fires and the throttle body cycles.
None of this happens with the first ecu when it overheats . If I spray it with something to cool it down or even sit an ice block on it , it runs normally.
 
Well for example, did the ECUs come from a junkyard or other unknown such as private party sale and you had them flashed? Or did you buy them from someone who flashes them and 'stands behind' them?
I purchased 1 off ebay from a site that has a warranty but because I bought an 05 ram ecu that's going into a 48 Windsor , they will not warrant it.
The 2 I have from B&G Chrysler , I'm not sure because they wont answer any emails or FB messages I send them ...
 
Earth to engine. Its sensor faults. Now, if you had access to a known good computer, or a truck that you could run your ecms in it may give you an idea whats goin on. Repeatedly throwing questionable parts at something and getting different results every time is an exercise in futility.
wouldn't that be great , they didn't import Rams into Australia so theres no chance of that happening im afraid.
This is exactly where I'm at , that's why I'm asking for someone that's reliable that will answer an email and take the time to help me out . The time difference is a real piss off
 
Im almost at the point where I give all this a miss , fit a dual plane inlet , a 500 holley , an MSD hemi6 ignition controller and a powertrain trans controller.
Adds up to a touch over $3000 , but at least I can tune a carb , the ignition is pre set with a tune for a 5.7 and I'm still waiting for an answer on the trans controller.
Or buy another new loom and ecu from hotwire or similar and possibly be stuck with the same issues $2000
I don't want to have to tune anything with a laptop and spend coin on dyno time .
At least if I do the first option , I have several systems to work with rather than one that runs or in my case doesn't run anything........
 
when it wont start when its hot , its because the fuel pump circuit doesn't fire . Normally when the key is moved to the on position , the fuel pump fires and the throttle body cycles.
None of this happens with the first ecu when it overheats . If I spray it with something to cool it down or even sit an ice block on it , it runs normally.
Is it the same problem Nikolaus Otto had when he test his engine the 1st time. He then integrated propeller to flywheel, cooling it down and solve the problem.

Since it difficult to order new part, why don't you install a separate electrical fan to cool down the ECU and see how's it going?
 
Is it the same problem Nikolaus Otto had when he test his engine the 1st time. He then integrated propeller to flywheel, cooling it down and solve the problem.

Since it difficult to order new part, why don't you install a separate electrical fan to cool down the ECU and see how's it going?

funny you should say that , i fitted a heat sink to the under side and cut a hole in the inner guard for it to stick through and fitted a 100mm computer fan over the top of the ecu.
Its not fixed but its better , at least i can turn it off at the petrol station and theres some hope it will start again
 
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