Rover V8 (TVR) - Starting issues
Discussion
1992 TVR Griffith 4.0 pre-cat
I am having some starting issues with the car. Cranks over, sometimes starts first time, other times, engine spins over and finally catches slowly and fires up, but revs may drop to 500 rpm, near stall then pick up again. I am trying to go through things systematically. I have RoverGauge too. Once its running, no problems, doesn't stall or hesitate.
When the engine is running and warmed up, RG gives no errors and apparently text book readings.
Yesterday I did the timing. Found TDC using a pistonstop and marked the crank pulley (it was barely 2* off crank markings). Using an advance timing light and with a helper, with a warm engine, revved to 4000 rpm and set timing to 28* BTDC. This gave me a static idle timing of about 15* which I know is perhaps a bit over the usual 12*.
I just checked the distributor for vacuum advance. Removed the dist cap. Rotor will turn several degrees and spring back by hand. I disconnected the vacuum hose from the plenum to the vacuum advance and sucked and blew on the hose. When sucking, no resistance was felt and nothing moved in the distributor (assuming it should on these types?).
More to follow, but
1) Is that timing set up going to be trouble (I haven't driven the car after adjusting the timing to see if it 'pinks' yet.)
2) Is the vacuum advance not working?
3) I am suspecting the positive battery wire to the starter is breaking down/fatigued (known weak spot) Will add a temporary cable alongside and check.
I am going to test fuel pressure, run a compression test and a few other things today.
Plugs, leads, cap, rotor, coil all fairly recent. Just changed the camshaft/lifters etc. timed properly etc.
I am having some starting issues with the car. Cranks over, sometimes starts first time, other times, engine spins over and finally catches slowly and fires up, but revs may drop to 500 rpm, near stall then pick up again. I am trying to go through things systematically. I have RoverGauge too. Once its running, no problems, doesn't stall or hesitate.
When the engine is running and warmed up, RG gives no errors and apparently text book readings.
Yesterday I did the timing. Found TDC using a pistonstop and marked the crank pulley (it was barely 2* off crank markings). Using an advance timing light and with a helper, with a warm engine, revved to 4000 rpm and set timing to 28* BTDC. This gave me a static idle timing of about 15* which I know is perhaps a bit over the usual 12*.
I just checked the distributor for vacuum advance. Removed the dist cap. Rotor will turn several degrees and spring back by hand. I disconnected the vacuum hose from the plenum to the vacuum advance and sucked and blew on the hose. When sucking, no resistance was felt and nothing moved in the distributor (assuming it should on these types?).
More to follow, but
1) Is that timing set up going to be trouble (I haven't driven the car after adjusting the timing to see if it 'pinks' yet.)
2) Is the vacuum advance not working?
3) I am suspecting the positive battery wire to the starter is breaking down/fatigued (known weak spot) Will add a temporary cable alongside and check.
I am going to test fuel pressure, run a compression test and a few other things today.
Plugs, leads, cap, rotor, coil all fairly recent. Just changed the camshaft/lifters etc. timed properly etc.
I see no issue with those timing figures, some of us run closer to 20 degrees without issue by using the full manifold vacuum modification.
You should feel resistance on the vacuum pipe, I'm guessing the diaphragm has split inside it but it should not affect the starting.
You need to determine what's missing when the no start occurs, if it cranks well then fuel and spark checks are worth doing.
You should feel resistance on the vacuum pipe, I'm guessing the diaphragm has split inside it but it should not affect the starting.
You need to determine what's missing when the no start occurs, if it cranks well then fuel and spark checks are worth doing.
Midway down the page is ECU start up sequence, may help a little.
http://www.g33.co.uk/pages/technical-fuel-injectio...
http://www.g33.co.uk/pages/technical-fuel-injectio...
Thanks for the comments.
I have run several data logs using Roverguage and nothing is leaping out to me. All parameters look good. Turning the ignition to start and the engine cranking shows a main voltage drop to around 7v then once it fires, straight up to 12.xv +.
Fuel pressure comes straight up to just under 40psi with ignition on. Once started and idling its around 30 psi. There doesn't seem to be anything wrong with the fuel supply. Fuel pressure is steady.
It seems to be getting spark.
Here's a link to a 15 second Youtube video of it starting and the start, then faltering idle issue.
https://youtu.be/rM6MquZU8so
Wondering if its a vacuum leak but I've checked all the vacuum hoses (two, dist-plenum, and stepper to fuel reg) and all connected with no splits.
I have run several data logs using Roverguage and nothing is leaping out to me. All parameters look good. Turning the ignition to start and the engine cranking shows a main voltage drop to around 7v then once it fires, straight up to 12.xv +.
Fuel pressure comes straight up to just under 40psi with ignition on. Once started and idling its around 30 psi. There doesn't seem to be anything wrong with the fuel supply. Fuel pressure is steady.
It seems to be getting spark.
Here's a link to a 15 second Youtube video of it starting and the start, then faltering idle issue.
https://youtu.be/rM6MquZU8so
Wondering if its a vacuum leak but I've checked all the vacuum hoses (two, dist-plenum, and stepper to fuel reg) and all connected with no splits.
That battery voltage is too low, and that can cause all sorts of tuning problems. I suggest you jJump start it from a running car and see whether that makes any difference. Also sort that vac advance out, and check the slow return valve is either fitted the right way round and working, or removed.
GreenV8S said:
That battery voltage is too low, and that can cause all sorts of tuning problems. I suggest you jJump start it from a running car and see whether that makes any difference. Also sort that vac advance out, and check the slow return valve is either fitted the right way round and working, or removed.
Thanks. Will try that. It doesn’t have a slow return valve fitted (between the distributor and plenum vacuum line) geeman237 said:
How would I do this? I’m not great with electrics. I do have a multimeter.
Set it to volts dc and put the black lead to a negative point on engine and the red to coil positive. Crank engine and observe voltage.
Repeat the test again with a good known negative from the battery if the voltage appears low.
Its not uncommon to see bad negatives on a Tvr.
As others say very low voltage on cranking. First measure the voltage at the battery terminals, if its the same (~7v) then battery is suspect.
If its higher, then check for voltage drop across your earth lead (leave meter in volts, one side on the battery and one side on a known good earth spot, ideally on the engine itself - would expect less than 1v shown on the meter during crank.
You can take similar approach on the positive side, but faults are usually down to bad earths or corroded cables.
If its higher, then check for voltage drop across your earth lead (leave meter in volts, one side on the battery and one side on a known good earth spot, ideally on the engine itself - would expect less than 1v shown on the meter during crank.
You can take similar approach on the positive side, but faults are usually down to bad earths or corroded cables.
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