Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing A heads up for KevFitz and any other Plus 4SS driv

Well Kev me Plus 4SS in disguise developed a cough and splutter on light throttle loadings, when i then put the boot down...... pops, bangs and stutters before we got lift off. Knew it wouldn't be plugs, leads, dirty fuel and the likes so suspected a field sensor and gambled it might the throttle position sensor. I decided to start here and the realized it was a modern Hall Effect type not the variable resistor / rheostat job which meant checking the voltage at the ecu, so i initially took the easy way out and unplugged the device to inspect the plug socket connections with a mag'glass, they looked a bit secondhand so cleaned 'em up and hey presto, throttle response back to what it should be. Ive done a couple of hundred miles and all seems ok.
So, if you are on Jenvey throttle bodies, as i am, you probably have the Giles and Penny TPS. It looks first class quality as does the moulded connection plug but the connections had become a but grubby, sufficiently grubby to create this issue. It does easily unplug for cleaning. It will probably save you silly money should you need to get the help of a dealer , who may not have experience anyway and bill you for many hours of fault diagnosis.

Thanks for info !!!!...will store that for the future.

Hope you didn't get burnt in Ibizia !!!!

While my old Mog has no EFI, I really appreciate top tips like this.

Some years ago when EFI confused most professional mechanics, a mechanic pal of mine spotted a Jag that stood on a forecourt for rather a long time... enquired to be told it was a non runner and the mechanics could do nothing with it... He asked to look under the bonnet, spun the engine, agreed a deal there and then, and the dealer asked when he would arrange pick up, he went back under the bonnet and shook all the EFI connectors around the engine bay, fired it up and drove off...!!!!

I post this just because it's an example, actually it's worth a thread of its own because it belongs to another car. But it should underline how important electrical contacts are. With my Sigma 4/4 it didn't run smoothly and the accelerator pedal had a bad reaction (not to be confused with my thread where I really had to change the gas pedal). Although I had a replacement throttle valve installed it didn't get any better. I bought a contact spray by chance just because it was on offer and Implayed arounf with it. The massive fault was the plug contact to the throttle. I sprayed the plug from the inside and especially from the outside. There where the rain water always runs in. Since then the gas reaction has completely changed. With half gas I have very good reaction. The car drives like transformed and you can dose the gas nicely. Just a bit of contact spray to a plug.

I'll keep that in mind for my fake Plus 4 SS too. Thanks.

Actually I have a mysterious problem with a small backfire on n. 1 cylinder when I put my foot down again after backing off. It doesn't happen all the time but it is very hard to track down the cause. TBs are well balanced so it is not that. I might try switching injectors, or swapping plug leads. I belive the Omex ECU uses a lost spark at top of the exhaust stroke so I should be able to switch leads. I need to check that I am correct before I start fidling.

I read all this stuff on Throttle Body EFI because I recently converted My 3.9 from Carb to an aftermarket TBI. Mine is a one model fits all unit. From 150 to 650 HP it says in the advertisement. Frankly it looks like an electronic Carb on a V8 as it is mounted on the same intake manifold as My Carb was mounted on. However: so far, other than it was difficult to get a steady idle (it is now at 1,000 RPM + or - 50 the unit has performed very well. I now have over 5,000 miles on it and did relocate the oxygen sensor inboard to the header that improved the idle but still can not get it under 1,000 RPM. I can live with that. But what do I do if it fails while away from home. I have a metal brief case with all the parts I need to convert back to a carb. Should the TBI fail I will call My Daughter and have Her send the brief case to Me. I even wrote a procedure for converting it back to a carb so I don't forget something. I could carry it on the luggage rack if I don't carry a passenger. No way in hell could I make a Field Repair.

Not engine specific but I think that with the age of many Morgans then some faults will occur. Age as much as mileage influence the condition.
At some stage the exposed wiring needs a clean up or replacement. I found this on my 2002 car. The front light wiring is exposed to water from the wheels. Bullet connectors are not waterproof and deteriorate. I replaced mine with new spades and sealed them with shrink sleeve.
Same applies to rubber components. I did a front to back replacement/flush of the fuel system on my 1993 18 year old 4/4 when fitting a new fuel pump. Included extra filter protection for the new pump, new flexi pipes etc.
Deteriorating electrical contacts is a fairly common fault inducer. Earth connections especially!

Agreed. I have just gone through all the earths.