So Zed is running rough.

Car is '54 UK GT DE has 30k miles. Vortech Supercharger, DW600cc, Kinetix SSV, Uprev GT MAF, AEM basic return fuel system, etc...Uprev tune.

It idles ok.
If held at constant revs or constant speed it runs ok.
Any acceleration when driving or reving when stationary and it runs lumpy almost like its missing a cylinder.
I have had a bit of a tapping/rattle at a certain rev range (usually between 2000rpm and 3000 rpm) that I thought was behind the dash, but I’m now wondering if its engine side of the bulk head and possibly related.

Things I’ve checked -

Plugs look good, but changed them anyway – no change
MAF is clean as a whistle
Throttle body looks clean
Looked for boost/vacuum leaks, nothing obvious but haven’t pressure tested yet – I hope to do that when I get home next week. Vacuum at idle is about 22 inHg and it does make boost but runs rough.
AFR on bank 2 seems normal when idling and driving but I haven’t got a sensor in bank 1 so that’s unknown.
I have had a bit of a tapping/rattle that I thought was behind the dash, but I’m now wondering if its engine side of the bulk head , Changed the fuel damper on bank 2 in case it was that, but no change.
I have also, removed the S/C cog belt so running n/a but no change.
Disconnected and bypassed oil catch can, taken off vac/boost pipe from Fuel Pressure Regulator


Any ideas on where to look next? :shrug:

 

Do a Compression test.

 

Thanks for the input.

I plan to do a compression test and a inlet leak test next. Then swap out the coil packs one at a time to eliminate them. After that I'll be scratching my head.

 

Mine was also running rough, turned out to the be the same DW600 cc injectors you have. Switched them out to 550cc bosch.

 

Hmmm, I hope not. They have only been in about 18 mths and a few thousand miles, after the first set I had (that was 2nd hand bought from here) had two faulty injectors.

 

Does the car sounds like a Subaru when driving or at Idle? Mine is doing this now and I am in search of the problem. I am having an issue now. I have changed my plugs. Now going to check for leaks and compression.

I did just fill up with gas before the issue raised. I have been thinking bad gas?

Let us know what you find out.

Chris

 

Sorry to hear but DW injectors aren't very good quality anymore from what I heard from my tuner. He said he had a few cars with faulty DW injectors, when DW sent them new ones, they came in a DW box but were Bosch injectors.

 

Update -

I leak tested my intake and hoses etc and found a couple of issues -









The first one could be a gasket issue, but the second two looks like the welds have given up after too many heat cycles maybe. The one on top is just a pin hole and the one at the boss seems like a small crack.

They are not massive leaks, but using a tyre inflater to pressurise the plenum It won't hold more than 10psi and within 5 seconds of turning it off the pressure has gone.
I don't know how long they've been there, so don't know if its my only issue but it's one I must address first.

I just hope the leaks haven't been there for some time, and maybe caused it to run lean causing more serious issues.

Now do I get my lovely blingy plenum re-welded....or put a stock one on for now.......

 

I'd just run a stock plenum with a spacer. The kinetix are known for breaking down under boost.

 

you can repolish the welds. just do that.

 

I haven't got round to getting the plenum leaks welded up yet, and although they do need sorting I wasn't convinced its the cause of my issues so decided to do a bit more fault finding.

Chris (Keyser) VERY KINDLY :thumbs: lent me a coil pack and a pair of VVT controllers to help me eliminate them as potential causes.

So one by one I swapped out the coil packs thinking it would probably be the issue......No change

I then tried the VVT controllers ......again no change . :thumbdown:

During all this, I noticed that one of my true dual exhausts was smoking more than the other and it was this one that seemed to be spluttering. This obviously concerned me.
The car never uses any fluids, ever, so thought it was unlikely a head gasket or anything more serious but decided to do a compression test anyway.

The first good news - Compression test was good. :thumbs: see bottom row below.




I then looked at the plugs I just pulled. Five of which were black as the ace of spades and one was not. These have only been in for a short amount of time since I had the issue.

Plugs from Cylinders 2,4,6,



and 1,3,5



This suggested that cylinder 1 may be running lean and all other cylinders were being run rich to compensate.

I looked at the plugs I removed when I first started getting the issue (not anywhere near as bad then) and although they looked pretty normal on the whole, it can be seen there are signs of number 1 running slightly leaner than the rest.

2,4,6



and 1,3,5




I then connected my OBD2 reader and loaded Torque up on the phone. No fault codes were present as before, but it could be seen that the ecu fuel trims were adding about +4 to 6% to bank one but removing - 7 to 9% to bank 2.
This again suggested that bank 1 (cyl 1,3,5) was not getting the same amount of fuel as bank 2 (2,4,6).

I'm now thinking an injector problem. Surely not, they're only two years old and covered about 10k miles. And after having faulty/ out of flow tolerance ones on my previous second hand set prior to that?? :blink:


I decided to remove the injectors, coils tested ok for resistance and functioned when given 12v.
I marked them up and put them back in the opposite banks. Once all back together I fired it up, and as suspected the smoke, popping and fault swapped to the other bank. The fuel trims were also opposite to before. :snack: Finally getting somewhere now.

I suspected the issue was with the injector now fitted to cyl 2. I had a spare injector from my previous set and although not flow matched with the others, I figured that it was worth a try.

After swapping the injector with a spare - It purrs like a kitten Haven't had a chance to go for a drive yet but idles and revs fine. Also the fuel trims are pretty even and now both +ve figures.

So I'll go for a drive tomorrow and see how it is.

I must say I'm pretty dissapointed that I potentially have another faulty DW600 injector. I will try and get them cleaned and tested first but not holding my breath.