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Tr7v8
Troy Cairncross

(2 posts)

Registered:
11/26/2014 05:44AM

Main British Car:


help! :-) Any ideas? TR7 3.9 efi.
Posted by: Tr7v8
Date: November 26, 2014 06:27AM

Hi there, looks like a good site to find info and chat about similar things!

Anyway, Im Troy from Australia.
Have a TR7 with a 3.9V8 with 14cux injection and a chip.
The engine has had a bit of work done, cam, port etc.

Anyway, so what is happening is that I drive it cruisy fast reving to 3500 to 4000 its fine, especially in 1st and 2nd. BUT Flat out revs from 2nd into 3rd, after the gear change and putting the foot down again she dies for about 1 second then goes again. Does the same from 3rd into 4th at full power.
I thought maybe its some sort of fuel pressure problem, like not enough, so made sure its got about the right pressure with a different regulator. I bumped it up from 2bar at idle and 2.5 WOT to 2.5 idle and about 2.8 WOT. That made no difference with the problem, but it does rev out better than with less fuel pressure.
I thought maybe its some sort of throttle position problem, ie, when i change gear I take off my foot then so it goes to its idle mode before the next WOT. So I tried putting the idle up to 2000, made no difference.
I wondered is it a fuel problem so I have a guage on the fuel rail that I videod under the bonnet to see if it showed a drop. And it held pressure perfectly, but when it did the problem, the fuel pressure actually went up slightly to 3.0 or 3.1. What does that mean? It is not the problem of too high fuel pressure that is upsetting the burn, as it does exactly the same thing with the standard regulator.
I tried driving in 3rd, reving it from say 4000 to 5500 about 4 times, and it did do the problem once of those times. Am I having some sort of engine pressure problem? Any ideas would be greatly appreciated!
Could timing have anything to do with this issue?


Tr7v8
Troy Cairncross

(2 posts)

Registered:
11/26/2014 05:44AM

Main British Car:


Re: help! :-) Any ideas? TR7 3.9 efi.
Posted by: Tr7v8
Date: November 26, 2014 07:50AM

Here's my engine bay. Does it look like I've done something wrong with my plugs in the intake?
14170059967325.jpg


rkas3882
randy kassed

(84 posts)

Registered:
05/30/2010 09:14AM

Main British Car:
1973 mgb gt rover 3.5

Re: help! :-) Any ideas? TR7 3.9 efi.
Posted by: rkas3882
Date: December 04, 2014 08:04PM

I had a similar problem with a chipped ecu for my 3.5, it was for a larger displacement engine and came from a TVR, the blip like you described was happening due to the chip. Do you have a different ecu you can try?


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