Wedge 350se misfire
Discussion
Been chasing an opening throttle misfire for some time now.
OK when cold
Occasionally behaves itself - got to Bristol on the Cornwall trip before it played up.
Starts when it gets warm - light throttle ok – floor it and it dies -
Changed rotor arm & cap (twice) - Lucas ignition leads.
Had the distributor rebuild by Power’s as the circlip had gone – but the misfire came back.
Bosch coil
New ignition amp
Thought I would change the fuel pump and injection relays just in case they play up when warm.
Dropped the cover and found this no relays for fuel pump, main injection and red ECU reverse polarity relay.
Can anyone advise? On the part numbers I should have?
Don’t know how it’s been running - is it normal practice to remove them when an alarm is fitted??
OK when cold
Occasionally behaves itself - got to Bristol on the Cornwall trip before it played up.
Starts when it gets warm - light throttle ok – floor it and it dies -
Changed rotor arm & cap (twice) - Lucas ignition leads.
Had the distributor rebuild by Power’s as the circlip had gone – but the misfire came back.
Bosch coil
New ignition amp
Thought I would change the fuel pump and injection relays just in case they play up when warm.
Dropped the cover and found this no relays for fuel pump, main injection and red ECU reverse polarity relay.
Can anyone advise? On the part numbers I should have?
Don’t know how it’s been running - is it normal practice to remove them when an alarm is fitted??
Hi Peter.
Not sure about the relays although I'm sure you should have a red "Pektron" relay which is a steering module relay that disarms the feed to the pump in the event of a crash.
The hot running issue could be related to a failing CTS...Or wiring to it....
Do you have a solid state FPR or an Adjustable, If the latter what is your Fuel pressure set to?
What is the condition of the spark plugs?
Was the king lead change as more often than not the supplied part is never long enough and the old one gets left on.
I would personally stop changing parts that don't need it and put the old parts back on...You could be opening up new issues.
Cheers
Ziga
Not sure about the relays although I'm sure you should have a red "Pektron" relay which is a steering module relay that disarms the feed to the pump in the event of a crash.
The hot running issue could be related to a failing CTS...Or wiring to it....
Do you have a solid state FPR or an Adjustable, If the latter what is your Fuel pressure set to?
What is the condition of the spark plugs?
Was the king lead change as more often than not the supplied part is never long enough and the old one gets left on.
I would personally stop changing parts that don't need it and put the old parts back on...You could be opening up new issues.
Cheers
Ziga
Misfire on my 350i when warm was down to failing NEW HT leads, failing NEW coil and failing NEW distributor hall effect pickup. Just because it's new don't discount it as working.
Top tip I was told was to run the engine warm in the pitch black and see if there are any visible sparks off the HT side of things. On mine it was lit up like a Christmas tree.
Also double check distributor cap is fitting well and rotor arm is a good quality one. Again had a new one fitted to the new distributor and it melted and distorted! Was replaced with a good quality original spec black bakelite type one and all was well.
Top tip I was told was to run the engine warm in the pitch black and see if there are any visible sparks off the HT side of things. On mine it was lit up like a Christmas tree.
Also double check distributor cap is fitting well and rotor arm is a good quality one. Again had a new one fitted to the new distributor and it melted and distorted! Was replaced with a good quality original spec black bakelite type one and all was well.
peter Richardson said:
Thought I would change the fuel pump and injection relays just in case they play up when warm.
Dropped the cover and found this no relays for fuel pump, main injection and red ECU reverse polarity relay.
Can anyone advise? On the part numbers I should have?
Don’t know how it’s been running - is it normal practice to remove them when an alarm is fitted??
I used to work in car security and we never removed anything of standard fitment... in fact fitting guidelines were so poor that hardly any major changed to the car's wiring were allowed in the end (to avoid comeback later) - you could break the starter crank wire and one ignition-switched feed and that was about it. Needless to say my installs are a bit more involved than that Dropped the cover and found this no relays for fuel pump, main injection and red ECU reverse polarity relay.
Can anyone advise? On the part numbers I should have?
Don’t know how it’s been running - is it normal practice to remove them when an alarm is fitted??
My initial thought was that as the fuel injection loom was originally an add-on to the Rover V8 the 'missing' relays could actually be found elsewhere on the car, but from the early days TVR incorporated them into the main relay panel (as yours).
Then I thought it could be that someone has replaced the loom and rather than mess around splicing into the relay panel they've left the entire loom intact, tucked up somewhere under the dash, and pulled the original relays out, maybe to use as spares or just because they thought them faulty.
No alarm I know of would replace the injection system and fuel pump relays with its own circuitry.
Yes we need a hotwire ECU circuit diagram to work that one out.
Does it have a rev limiter (usually fitted next to the coil) if so remove it.
Check the advance mechanism (when cold, and when warm) in case things are sticking. TO do this, use a strobe light on the timing marks.
After eliminating the spark generation, the next culprit could be the ECU playing up. Ignition pulses feed into the ECU and this then generates the fuel pulses for the injectors.
Does it have a rev limiter (usually fitted next to the coil) if so remove it.
Check the advance mechanism (when cold, and when warm) in case things are sticking. TO do this, use a strobe light on the timing marks.
After eliminating the spark generation, the next culprit could be the ECU playing up. Ignition pulses feed into the ECU and this then generates the fuel pulses for the injectors.
Hi thanks for your reply’s
Yep it’s a hot wire 4ltr 1990 vintage.
Had a one off king lead made to get correct length. Was thinking of mounting the Coil on the engine to get a shorter lead? Seems a long way for the spark to go. Must lead to some loss of spark power?
Just changed the temperature sensor. (CTS)
Also treated it to a new set of spark plugs
No rev limiter fitted.
It has a standard FPR – The FPR and the fuel pump was the next things in the list to change.
The thinking was fuel pressure dropping of as things warm up.
Yep it’s a hot wire 4ltr 1990 vintage.
Had a one off king lead made to get correct length. Was thinking of mounting the Coil on the engine to get a shorter lead? Seems a long way for the spark to go. Must lead to some loss of spark power?
Just changed the temperature sensor. (CTS)
Also treated it to a new set of spark plugs
No rev limiter fitted.
It has a standard FPR – The FPR and the fuel pump was the next things in the list to change.
The thinking was fuel pressure dropping of as things warm up.
peter Richardson said:
Yep it’s a hot wire 4ltr 1990 vintage.
It has a standard FPR
Hi Peter...It could be a fuel issue..If its a standard FPR then i should imagine you are not getting enough fuel.It has a standard FPR
My 350i has an adjustable FPR which is set to 36-38psi at WOT....I believe the 390SE had an adjustable FPR and was set to around 42psi WOT...This doesn't sound much but i have witnessed a rise of 2bhp by increasing the fuel pressure to 40psi..However this puts the emissions to unacceptable values for the MOT.
I have also noticed at 42psi the car will not rev at high speeds...Almost to the point of cutting out.
If you have a standard solid state FPR that is set to 36psi then i should imagine you need more fuel...Are your plugs showing any whitening associated with running lean?
You definitely don't want to do that.
Cheers
Ziga
It's hard to be certain from the fuzzy photo but it looks like the relay sockets have terminals in them. You normally only insert the terminals once you've crimped them onto the wires, which is why I was thinking they had been connected to something at some stage.
Once might have hoped that since the 400SE hotwire was in production by the time the 350SE was introduced, the relay panel would have been altered to accomodate the later injection wiring... but being TVR maybe they shoved an old 350i flapper loom in and bundled the hotwire bits in a dark hole.
Either way the OP needs to be under the dash with a torch and mirror
Once might have hoped that since the 400SE hotwire was in production by the time the 350SE was introduced, the relay panel would have been altered to accomodate the later injection wiring... but being TVR maybe they shoved an old 350i flapper loom in and bundled the hotwire bits in a dark hole.
Either way the OP needs to be under the dash with a torch and mirror
Hi
Thanks for your input - finally got to the bottom of my reoccurring flat spot.
Problem was an intermittent connection on the live feed to the Air flow meter.
One of the prongs has broken off the female connecting pin in the plug.
Silver foil jammed into the connector temporary fixes the issue
Anyone have experience in replacing this connector?
A Durite Junior Power Timer 6 way connector looks similar but will it fit??
Cheers
Thanks for your input - finally got to the bottom of my reoccurring flat spot.
Problem was an intermittent connection on the live feed to the Air flow meter.
One of the prongs has broken off the female connecting pin in the plug.
Silver foil jammed into the connector temporary fixes the issue
Anyone have experience in replacing this connector?
A Durite Junior Power Timer 6 way connector looks similar but will it fit??
Cheers
pricha38 said:
Hi
A Durite Junior Power Timer 6 way connector looks similar but will it fit??
Cheers
It's a 7-way on the flapper; Vehicle Wiring Products certainly used to sell a line socket that would fit (7-way) but it's been a while since I bought one. I would stick my neck out and say that if they do a 6-way, it should fit A Durite Junior Power Timer 6 way connector looks similar but will it fit??
Cheers
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