hot stumble problem, help needed
03-10-2015 | 03:36 PM
#16
4.7 to be precise... witchhunter has the details: http://www.witchhunter.com/flowdatapix/b0280150803.jpg
03-10-2015 | 04:00 PM
#17
My guess is overheated injector drivers. Install ballast resistors to protect the driver circuit.
Second guess is some bad grounds.
Chased a similar problem in 89 track car for over a year. Solved by installing ballast resistors - 1 ohm/10 watt on the two driver paths.
Second guess is some bad grounds.
Chased a similar problem in 89 track car for over a year. Solved by installing ballast resistors - 1 ohm/10 watt on the two driver paths.
03-10-2015 | 06:55 PM
#18
Thread Starter
Drifting
Alternator output good Blade, It even had a new alternator put in not so long ago.
John's injectors are the correct impedance just larger, must be new to the market.
Onset i would say is similar, the last track day was the first time we had witnessed it. It seems as if this issue is becoming more and more frequent, which is good for us as in the past it would never play up.
Im going out on a limb but i do think its possible that my current tune on the car is slightly richer then the previous. Making the symptoms more exaggerated.
Here is another thing after talking to the owner, boost makes a difference to the severity of the condition. In Targa Tasmania the car was running 14psi. Once the symptom came on the turned it down to 10psi and it alleviated the severity. Actually thinking about it now we have the boost set to around 17psi which would make it worse.
Do you mean the NTCII or is there a different sensor you are taking about?
Great information Tom,
The car will be back it a few days and i will check that wiring to the Coil. I considered opening the DME and dying to find what part was overheating but at the thought of how hot it was i declined. when the Customer turns up at the shop i will get out the thermal gun and see if i can pinpoint the circuit.
Thanks for your thoughts slivel.
I had thought of the grounds, the major grounds from the battery to the body and body to engine have been remade along with the 2 main grounds from the DME to the engine.
Regards
Sean
From memory, stock injectors are supposed to be around 5 Ohms... I never found any larger after market injectors with that impedance but I haven't looked recently.
Interesting that the problem started with stock injectors... I wonder if they were still within the specified range for impedance? From what you wrote earlier it seems that the problem is not only more aggressive with the new injectors but the onset is also earlier.
Interesting that the problem started with stock injectors... I wonder if they were still within the specified range for impedance? From what you wrote earlier it seems that the problem is not only more aggressive with the new injectors but the onset is also earlier.
Onset i would say is similar, the last track day was the first time we had witnessed it. It seems as if this issue is becoming more and more frequent, which is good for us as in the past it would never play up.
Im going out on a limb but i do think its possible that my current tune on the car is slightly richer then the previous. Making the symptoms more exaggerated.
Here is another thing after talking to the owner, boost makes a difference to the severity of the condition. In Targa Tasmania the car was running 14psi. Once the symptom came on the turned it down to 10psi and it alleviated the severity. Actually thinking about it now we have the boost set to around 17psi which would make it worse.
Do you mean the NTCII or is there a different sensor you are taking about?
I once used a Nology coil "amplifier" that made the DME smoking hot. I burned the bajesus out of my finger trying to find what was causing the DME to be so hot. Spoiler alert, it was the ignition transistor... Removing that reduced the DME temp dramatically. If you have stock everything, I'm not sure what would cause two different DME's to heat up like that.
Just some random thoughts that seem unlikely to help... The ignition pulse if first produced in the DME. That signal then goes to KLR9 AND to the tachometer. It seems possible --in theory anyway-- that a faulty tachometer (or dash harness) could screw up the initial ignition pulse somehow. Also, you mentioned rebuilding the harness, but it might be worth noting that the final ignition pulse runs from DME1 to that 14 pin connector on the firewall, and then from that connector to the coil -- i.e. not in the engine harness you rebuilt...
Just some random thoughts that seem unlikely to help... The ignition pulse if first produced in the DME. That signal then goes to KLR9 AND to the tachometer. It seems possible --in theory anyway-- that a faulty tachometer (or dash harness) could screw up the initial ignition pulse somehow. Also, you mentioned rebuilding the harness, but it might be worth noting that the final ignition pulse runs from DME1 to that 14 pin connector on the firewall, and then from that connector to the coil -- i.e. not in the engine harness you rebuilt...
The car will be back it a few days and i will check that wiring to the Coil. I considered opening the DME and dying to find what part was overheating but at the thought of how hot it was i declined. when the Customer turns up at the shop i will get out the thermal gun and see if i can pinpoint the circuit.
I had thought of the grounds, the major grounds from the battery to the body and body to engine have been remade along with the 2 main grounds from the DME to the engine.
Regards
Sean
03-30-2015 | 07:12 PM
#20
Thread Starter
Drifting
Hi Guys,
Update time, We installed an external ignition module on this car that John had sent us. Started straight up and the customer picked the car up and drove it home. About a 45 minute drive. All went well.
On the Saturday we had a track day where we would be able to test the new module and see if there would be a difference.
The track day was at wakefield park, about a 2 hour drive by highway at 110kph from the customers home. Unfortunately he only got 20 minutes up the highway before the car stopped completely and he towed the car back to our shop.
Turns out the new module died. The way i am looking at this is that the original problem is still here and it has affected the new module to the point that it failed.
We replaced the new module with another that we had and performed a few tests between our own car and the customers. Using an oscilloscope we probed the trigger wire going to the new module (pin 32 on the DME) on both our own car and the customers the image was the same. (basically 12v with a square wave dip) We then probed the output from the module to the coil. Again the image looked the same. This somewhat eliminates the output stage. Although i must tell you guys until we actually correct this i am reluctant to eliminate anything.
I then tested the coil on both the cars resistance between the - and out put was 7620 ohms there abouts on both and also between the + and - terminal was 1.0 ohm on both.
With ignition turned on we had 12.7v on the + and 12.2v on the - on our car
the customers car has 12.6v on the + and 10.2v on the negative. The coil on the customers car was also making a faint but noticeable high pitched buzzing noise. At this time i moved the output high tension lead, the buzzing disappeared and the V at the - terminal was now at 11.3v
We don't know what caused this but we then replaced the coil lead with another new one ( we had only replaced the entire high tension lead set only a month or two before)
Now i think Tom was on a thought with the input going to the original DME could somehow have an effect on the ignition module(from the tacho). Do you think this could be the case
As a point of interest when we installed the Vitesse MAF kit to this car the customer also provided us with a shift light cluster to install. This piggybacks off the tacho trigger wire. Makes me wonder if there is an issue with the instrument assembly and when we attached the shift light to the mix this is when the problem then got aggravated even mores.
We will keep digging
Regards
Sean
Update time, We installed an external ignition module on this car that John had sent us. Started straight up and the customer picked the car up and drove it home. About a 45 minute drive. All went well.
On the Saturday we had a track day where we would be able to test the new module and see if there would be a difference.
The track day was at wakefield park, about a 2 hour drive by highway at 110kph from the customers home. Unfortunately he only got 20 minutes up the highway before the car stopped completely and he towed the car back to our shop.
Turns out the new module died. The way i am looking at this is that the original problem is still here and it has affected the new module to the point that it failed.
We replaced the new module with another that we had and performed a few tests between our own car and the customers. Using an oscilloscope we probed the trigger wire going to the new module (pin 32 on the DME) on both our own car and the customers the image was the same. (basically 12v with a square wave dip) We then probed the output from the module to the coil. Again the image looked the same. This somewhat eliminates the output stage. Although i must tell you guys until we actually correct this i am reluctant to eliminate anything.
I then tested the coil on both the cars resistance between the - and out put was 7620 ohms there abouts on both and also between the + and - terminal was 1.0 ohm on both.
With ignition turned on we had 12.7v on the + and 12.2v on the - on our car
the customers car has 12.6v on the + and 10.2v on the negative. The coil on the customers car was also making a faint but noticeable high pitched buzzing noise. At this time i moved the output high tension lead, the buzzing disappeared and the V at the - terminal was now at 11.3v
We don't know what caused this but we then replaced the coil lead with another new one ( we had only replaced the entire high tension lead set only a month or two before)
Now i think Tom was on a thought with the input going to the original DME could somehow have an effect on the ignition module(from the tacho). Do you think this could be the case
As a point of interest when we installed the Vitesse MAF kit to this car the customer also provided us with a shift light cluster to install. This piggybacks off the tacho trigger wire. Makes me wonder if there is an issue with the instrument assembly and when we attached the shift light to the mix this is when the problem then got aggravated even mores.
We will keep digging
Regards
Sean