Hi, I have a 3 door cosworth converted to 4x4. It is running L8 ECU with MSD closed loop chip with 83lb injectors. The turbo is a GT3076R and the engine is low comp 7.5CR with bd14 inlet cam with CNC head. I have been having this problem for a while now, basically if I drive at a constant 70mph in four or fifth gear and applying a constant amount of light throttle peddle the car seems to hesitate, then it goes normal, then it hesitates and cycles through like this. If I use the same amount of throttle accelerating from say 50mph to 70mph, once it has finished accelerating and the engine is under less load it begins to hesitate/hold back. If I plant my foot to the floor it builds boost as normal (and goes like F%&K). Most of the engine sensors are pretty newish. I have checked fuel pressure and it is fine, the co is at 3% at idle as I am not running the lambda. It has had a new throttle position sensor, new blue/brown, new phase and crank. Any help would be much appreciated. Thanks, Neil.

 

I would call MSD for advice

Steve

 

Mine did the same and it turned out to be something to do with the chip, once that was changed never happened again.

 

Hi Simon, I am beginning to suspect the chip is the problem as I have checked everything I can think of. What chip did you have problems with and who did you use to get a better chip. Cheers, Neil.

 

Turbosystems are good

Steve

 

As above give tony a call. He made me an off the self chip and it has been spot on!!

 

The chip that was in was a superchips one, noble motorsport in chesterfield sorted it with a new chip and a session on the rollers, turned it into a different car.

 

Hi

Any updates to this ?

mine is doing what seems to be exactly the same.
although also having this holding back issue in the lower gears applying very gentle throttle.

running greens, on a T3, wsted spark and closed loop, newish sensors all arround

 

Hi, I have fitted standard injectors and stage 1 chipp and the car drives absolutely perfect so I can only assume it is the chip/map now. What chip do you have in your car?

 

Tps adjusted ?
Matched to loom (pf01 v pf09)
Checked volts ex tps (track breaks)

 

Easiest thing to do is ring James at MSD and give him the serial number on the chip and he will give you the reported spec details that belong to that map - you will then know if you have something amiss - you may even get something sorted by them so best to call them first before buying a new chip

 

Just saw chip changed cleared fault...doh

 

Lets just clarify one thing before we go any further, just to be sure, as its odd nobody else has mentioend it...

You say you are running a chip that requires a lambda sensor to work properly... without one?

 

I'm with Stu on this one

MSD have amazing customer service too

Give them a call. They were great to deal with, even from New Zealand!

 

Hi Stu, yes that is correct, no lambda. I will get the lambda up and running and see if this solves the problem. Thanks, Neil.

 

Really though the base map shouldn't be far enough out to cause a running problem if the lambda goes down

 

Not on a modern system James, maybe, but on a 30yr old speed density system, a light hesitation when cruising is hardly clasified as "a problem" on a car with 1000cc injectors and a hardware fault logged in the ECU due to a totally missing sensor. Well, not in my book anyway.

Plus, given the lambda will normally correct around minor issues with the car, such as small vacuum leaks, old lifters, poor compression, incorrect fuel pressure etc, who knows whats actually causing the issue?
In fact, is the CO screw set as per instructions for a closed loop car? That in itself is enough to create this kind of issue, since it actualy ISNT a closed loop car at all at the moment.

Regardless... you simply CANT start looking for faults when you already know your engine management system has a sensor missing... Well, we certainly wouldnt anyway, as a simple 1 decimal change at this injector size can change the AFR from 14:1 to 11:1 at certain low speed areas of the map so we wouldnt waste or time until we knew all sensor inputs were correct.

 

It's obviously a big enough of a problem to the customer, for him to put a post on here. Going by his first post on the thread, I'd say it's more than a light hesitation though!

 

I sympathise with his problem, which is why I have responded to the topic.

My last reply was to you directly James, not him.
You suggested his lambda being disconnected shouldnt cause his problem. I just corrected you.

 

Hi guys, The instructions state 2.7% - 3% CO at idle with hot engine. This is what it is set at the moment around 3%. Do I need to alter the CO screw when I hook up the lambda sensor? Thanks for the help and advice. Neil.

 

You need to read the closed loop supplement sheet that came with it too mate. All info is in there... its currently set WRONG for a closed loop chip.