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tr 5 bogging down


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Hi All,I realise that I am asking about a TR5 in the TR6 forum but there seems a lot more info about the metering unit here.

I'm trying to get a TR5 to accelerate from idle instead of bogging down.It seems to be over fueling at idle. It has cp throttle bodies with air bleed screw and push on fuel return pipe.

Ignition timing set at 11 degrees btdc at 850 rpm

Checked fuel pressure at metering unit gives 100psi

I have 6 inch hg vacuum at the manifold and the 6 inlet ports are all within 1/2 a unit of flow (in this case kg/hr) showing 2 to 21/2 and have tested at part throttle -again all showing more or less equal flow.

I changed the throttle spindles (which rectified the play and adjusted the butterflies to be best seating possible.

This greatly improved the idle(which was all over the place) giving me a stable idle that can be adjusted down to 650 rpm but still very very rich

I have checked the mixture control unit and it has got blue springs fitted ,should'nt they be silver or red.? thus leaning the mixture more?

I have trolled through many posts but non seem to give any info about the effect the different springs have.

any help or comments would be very much appreciated thanks

Mike (malaga spain)

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Er.... is the diaphragm ok?

Also make sure that the fuel cavity spill return line is clear. They can block at the small ‘rubber’ hose under the l/h wheel arch.

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Is your 6" Hg at idle? Seems a bit low.

 

I have a TR5 cam in a bored 2.7 litre TR6 engine and my idle vacuum is generally around 10" Hg. Many TR6 engines have a much higher idle vacuum than this.

 

BowerPower in Sydney developed a fuelling curve for this engine. At 6"Hg vacuum it's getting fed 27% more fuel than at 10"Hg. There was no new spring fitted when the MU was recalibrated but I don't know whether a PO had fitted a non standard spring at sometime in the past.

Edited by Mike C
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The blue springs are for the saloon car, not sure why, (I think more inlet vacuum) but the TR5 springs should be both red. With 7" of vacuum.

What does the fuel pressure do when you try to accelerate?, I would increase it a little to 105psi. to cover the drop at acceleration.

Have you checked that the diaphragm on the MU holds vacuum?

Do you know what the MU unit is timed up at?, #6 port at the MU should just be opening at 10 degrees before tdc.

John

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Mike,

The timing marks might have slipped - the rubber in the torsion damper distorts. I'd set the tickover by turning the disy a feww mm to and fro slowlty until you get the best rpm. Over-retarded spsrks will cause bogging.

Peter

Edited by Peter Cobbold
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Thanks for the quick replies.I will check if the diaphragm holds vacuum and that the pump is timed correctly.

The metering unit looks as though it has been overhauled recently as it is very clean and there is clean yellow anti tamper paint on the screws.

I forgot to say that the engine was rebuilt etc in 2017.Also a bosch pump kit was fitted along with a rebuilt long PRV -non adjustable

Edited by mikespain835
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Mike,

 

Every time mine has been lumpy pulling away until it gets to about 2,000 revs it is the butterfly balancing that has cured it.

 

My issues have been that at tickover the car is running on two cylinders with a good mixture, the other four cylinders the butterflies have been tight shut but the injection still gives them a slug of fuel on each cycle so they just get way, way over rich with dirty plugs just 'oribble. When the throttle opens it takes quite a few cycles to blow the cylinders and plugs clean when the engine can start to run nicely and pull properly.

 

When balanced the engine still runs a little rich, as it is designed to do, but all cylinders are singing from the same hymn sheet and when the throttle opens they all respond together. My car runs at 6" to 7" vacuum which I believe is correct for a CP PI

 

 

.Alan

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Hi Mike. I was recently called out to look at a car that was suffering with the same problem. My friend had just finished setting up the car but was not happy with it’s pick up from idle. He had balanced the butterflies with an air flow meter and the engine running at idle. ( He considered the butterfly adjustment to be at it’s most sensitive with the lowest rpm.) I suggested me rebalanced the butterflies with the rpm at 1500 as per the brown book. This worked for us and might hopefully solve your problem. I assume the brown book states 1500rpm as this is a typical low power setting that the car will be asked to accelerate from on the road, and therefore it is more important that the butterflies are accurate at this power rather than idle.

All the best,

Ashley

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On ‎9‎/‎20‎/‎2018 at 12:20 PM, mikespain835 said:

Hi All,I realise that I am asking about a TR5 in the TR6 forum but there seems a lot more info about the metering unit here.

I'm trying to get a TR5 to accelerate from idle instead of bogging down.It seems to be over fueling at idle. It has cp throttle bodies with air bleed screw and push on fuel return pipe.

Ignition timing set at 11 degrees btdc at 850 rpm

Checked fuel pressure at metering unit gives 100psi

I have 6 inch hg vacuum at the manifold and the 6 inlet ports are all within 1/2 a unit of flow (in this case kg/hr) showing 2 to 21/2 and have tested at part throttle -again all showing more or less equal flow.

I changed the throttle spindles (which rectified the play and adjusted the butterflies to be best seating possible.

This greatly improved the idle(which was all over the place) giving me a stable idle that can be adjusted down to 650 rpm but still very very rich

I have checked the mixture control unit and it has got blue springs fitted ,should'nt they be silver or red.? thus leaning the mixture more?

I have trolled through many posts but non seem to give any info about the effect the different springs have.

any help or comments would be very much appreciated thanks

Mike (malaga spain)

Hi Mike,

Your Hg looks low to me? What sate of tune is your engine? Do you have a standard cam for your TR5? If not in my experience the MU often needs to be re calibrated as the engine will run too rich. Also you need to check for vacuum leaks, the servo unit and the rubber balance pipes between the manifolds are good starting points, as is the manifold pipe to the M/U. Lastly have you done a compression check on a hot engine? I am not an expert on the TR5 but if I remember correctly the TR5 has a differently calibrated M/U to a CP TR6?

Bruce.

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If you still want to have a go at adjusting the different springs etc- Lee Janssen prepared this MU  adjustment guide maybe 10 years ago:

His site is:

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=6&cad=rja&uact=8&ved=2ahUKEwiYgNvyss7dAhVIUt4KHaPoDlsQFjAFegQICRAB&url=http%3A%2F%2Fwww.tiggersavage.com%2Ftr6_overview.htm&usg=AOvVaw3zx6NlJkHJFMGB8_Piq-ZV

The relevant part of the site is:

http://www.tiggersavage.com/pi_overview.htm

 

 

Edited by Mike C
Web site location didn't copy.
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Hi again

right-

The tube to the atmospheric pressure side of the control unit is clear

Checked for vacuum leaks all good and no leak from  control unit diaphragm.

checked over fueling lever is fully returning and it has gap between cam and lever.

checked metering unit timing-set as per brown book for cp engine,just see the opening at top of No 6 port.

Tried  adjusting the ignition timing not much change

reset the throttle bodies at 1500 revs.

Although a very slight improvement it is stil nowhere near right or driveable.

what I have noticed  is when cold it runs a bit better and as it warms up it gets worse and really smells of fuel from exhaust and plugs are sooted up.

I feel that what Mike C says is relevant as there are blue springs fitted.

I have been searching for some red springs but to no avail from the usual suppliers, will send an E-mail to malcolm at prestige injection,anyone got any ideas where I could get some,also any more ideas as to anything else that could cause the problem?

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Did the MU work OK before the engine rebuild or is it an unknown?

If the moving-stop balance srping is lacking or weak it will run rich even at correct fuel pressure. Number 46

LUCAS_BLOWUP.gif

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HI Peter,

I'm afraid it is unknown,however the metering unit does look prestine as if it is a recon unit, when I removed the adaptor for No 6 outlet the o ring was supple and no signs of age ,and all the connections are sqeaky clean.All I know is that the engine was reconditioned last year and has been hardly driven since.

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I'm sure you will have to have the MU recalibrated if you get some red springs, but if you want to be adventurous, take off the black cap on the MU, mark the position of the screws/rings, undo only the largest lower ring, and turn the whole set anticlockwise, perhaps a 1/4 of a turn at a time and restart, but put the black cap back on and this will make sure to hold the vacuum.  Screwing anti clockwise will weaken the mixture, clock wise will enrich the mixture.  Doing it this way changes all the settings at the same time, if it doesn't make an improvement put it back to where you started, and have the unit calibrated correctly.  Have you tried Neil Ferguson for the springs, sometimes he's on here?

 

 

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1 hour ago, mikespain835 said:

HI Peter,

I'm afraid it is unknown,however the metering unit does look prestine as if it is a recon unit, when I removed the adaptor for No 6 outlet the o ring was supple and no signs of age ,and all the connections are sqeaky clean.All I know is that the engine was reconditioned last year and has been hardly driven since.

Hi Mike, I wonder if storage has cused the moving-stop to seize ...rusted with old ethanol fuel in it ?  The m-s might be stuck where it slides into the MU housing so you could try spraying WD40 after removing the rectangular plastic  cover. Peter

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  • 4 weeks later...

Hi again---problem solved.

I removed the injectors and  put them on a cleaning rig I have made (basically a plastic deposit to a bosch pump and filter through an adjustable letby valve to a return pipe tee'd into feed pipe with pressure gauge) anyway fitted the injectors one by one and 4 out of the 6 had leak by and more like jets of fuel rather than a nice cone. After flushing them through I managed to get them clean and a good conical spray.Refitted them and after bleeding the injectors it ran quite well.After changing the blue springs to silver or plain springs it roared !went for a test drive and great response all through the revs.Job Done!

I first thought that the rough running was down to worn throttle spindles,after changing them and changing to ball and socket throttle rods it improved but nowhere near enough.The biggest improvement was cleaning the injectors and the icing on the cake was changing the springs.

Thanks to everybody for your input and help ,it does help to discuss these problems as it makes one think of all the variables to cure a problem

thanks again-Mike

 

 

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1 hour ago, mikespain835 said:

Hi again---problem solved.

I removed the injectors and  put them on a cleaning rig I have made (basically a plastic deposit to a bosch pump and filter through an adjustable letby valve to a return pipe tee'd into feed pipe with pressure gauge) anyway fitted the injectors one by one and 4 out of the 6 had leak by and more like jets of fuel rather than a nice cone. After flushing them through I managed to get them clean and a good conical spray.Refitted them and after bleeding the injectors it ran quite well.After changing the blue springs to silver or plain springs it roared !went for a test drive and great response all through the revs.Job Done!

I first thought that the rough running was down to worn throttle spindles,after changing them and changing to ball and socket throttle rods it improved but nowhere near enough.The biggest improvement was cleaning the injectors and the icing on the cake was changing the springs.

Thanks to everybody for your input and help ,it does help to discuss these problems as it makes one think of all the variables to cure a problem

thanks again-Mike

 

 

Hi Mike !  Did you actually find out what was causing the injectors on 4 & 6 not to spray properly? Was it bits of 'O' ring rubber?

Bruce.

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