500HC Problems with tickover on start up

[waggy]

Hi.

i have a 1994 Griff 500HC pre serp. My problem is when i start the engine, it wont tickover and i have to rev it and hold throttle till engine gets warm and then it ticksover at 1100 to 1300rpm varying.which is way too high.

I have run RoverGauge and cannot see the problem, the MAF 30% -35% , Both LAMBDAS are fluctuating between 0 and plus 50%, Idle bypass varies between 39 and 50.

This problem started when i changed oil and removed distributer to spin the oil pump to get pressure. I have done this lots of times over the 20 yrs ive owned the car. I checked timing and it was out, so I adjusted it to 12deg btdc on idle. If i add more retard then engine rpm increases to 2000rpm on idle.

never had this problem before. it used to, on cold start, tickover at 1500rpm and after i drove off it dropped to 900RPM . Hot start it used to stay around 900 all the time.

any help appreciated.

first pic is ignition on, engine not started ,, second pic is tickover after engine warmed up.

Edited by waggy on Tuesday 19th August 12:01

[waggy]

Sorry realised the MAF was on Linear..

this is when MAF on Direct.



thanks

Alex

[haaren]

Do you checked on vacuum leaks?

[waggy]

I screwed down the Air Bleed screw on the plenum and the revs dropped and stalled the engine. if there was a leak this surely wouldnt happen. I have also cleaned the stepper motor and it seems to work ok.

my problem is when i start a cold engine theres no tickover and it wont run without throttle. it seems okay when engine has warmed up.

thanks for response

[Belle427]

You could have a misfire which will show as a lean condition and it will add fuel which your lambdas seem to be doing.
If the distributor is the only thing you touched i would verify all looks good, leads are seated etc.

[waggy]

Belle427 said:

You could have a misfire which will show as a lean condition and it will add fuel which your lambdas seem to be doing.
If the distributor is the only thing you touched i would verify all looks good, leads are seated etc.

Its always run a bit lumpy on tickover, its been like that since i put a new high lift cam in it in 2007. 3 yrs ago i replaced the coil, plugs, rotor cap and leads.

I will check leads are seated ok and the plugs to see if they are all the same colour.

thanks
Alex

[waggy]

Rechecked timing, with plugs out checked TDC as it doesnt relate to markings on flywheel. Noticed there is a indentation on the flywheel where TDC is. timing is 12deg btdc. cleaned plugs and checked all leads, cleaned Cap and rotor arm.

started up and had to use throttle to keep it running as before. when temp reaches 50deg it will tickover at 1200rpm.

Its always run a bit lumpy since i replaced a worn camshaft in 2007, with a higher lift one. but the tickover was always about 900rpm,

tried altering the Main air bleed screw on the plenum. it was set at 2 turns out. turned it in and engine became very lumpy so put it back to original position.

Stepper motor seems to work okay, nice and clean, is there an easy way of checking its operation.

thanks for any help

[Loubaruch]

The indentation on the flywheel is not TDC, the timing marks are engravings some distance from the notch. If your vibration damper has perished and the timing marks have shifted then you need to set up timing from basic principles.

[waggy]

Loubaruch said:

The indentation on the flywheel is not TDC, the timing marks are engravings some distance from the notch. If your vibration damper has perished and the timing marks have shifted then you need to set up timing from basic principles.

I have heard that about marks shifting. but mine hasnt changed in 20 yrs of ownership.

The original rover timing marks on the flywheel are about 30deg to right of the TDC pointer. When I checked the TDC using a dial gauge it fell exactly on the indentation on the flywheel. Either TVR made the mark or a previous workshop. this mark hasnt moved since i did the timing in 2007. The pointer bolted to the front plate which i havnt moved could have been put in a different position by TVR.

My Car is one of the first Griff 500 built feb 1994, I dont have a 100amp fuse fitted and loom looks more like a 400. Im guessing TVR just utilised 400 parts to build the first 500s. Ive worked on the wiring on a 1995 Griff and its completely different to mine.

In image the black line on right is original TDC mark on flywheel. white line far left is actual TDC middle line is 12deg BTDC

Edited by waggy on Thursday 21st August 13:16

Edited by waggy on Thursday 21st August 13:25

[Belle427]

Something does not look right there, im sure i see the word After stamped on the pulley ie ATDC?
That would make the original black line somewhere right if that makes any sense.
Wondering if the pointer has been bent somehow?

Edited by Belle427 on Thursday 21st August 14:54

[waggy]

Belle427 said:

Something does not look right there, im sure i see the word After stamped on the pulley ie ATDC?
That would make the original black line somewhere right if that makes any sense.
Wondering if the pointer has been bent somehow?

Edited by Belle427 on Thursday 21st August 14:54

Thats correct, to the left of the TDC black line is 'After' and to the right of TDC its says 'Before'.

I drew the black line on original TDC mark. as it wasnt clear in photo. If you look on white line next to pointer theres an indentation exactly where TDC actually is. It looks like TVR placed the pointer to the left of where it usually sits and made an indentation for TDC.

I bought the car in 2004 with only 20k miles on it and the bills show only servicing and replacement fuel pipe. so no major work was done.

[eliot]

Think you are being somewhat over-cautious removing the dizzy to prime the pump for a simple oil change - that's the sorta thing you do on a new build or after replacing the pump. Pre-fill the new filter with oil and just swap it over reasonably quickly.

[waggy]

I agree with you.

I usually change the oil and filter and turn engine over with fuel pump disconnected, to see if oil light goes out. if it doesn't straight away, I remove distributor and pump it with a drill. Always done it this way. wouldn't want to start engine with no oil pressure.

[Belle427]

Even on a serp engine I don't think the pressure light goes out just cranking alone.
Some people on a pre serp put a new primed oil filter on before draining the sump and then re fill and just send it.