John Speake

After replacing most of the igntion components it was about the only thing left :-)

I wanted the injectors cleaning anyway, but to minimise down time I bought another used set, had them cleaned and flow tested, then swapped over. There was certainly a preformance improvment, and the vibration/misfire had gone away. I seem to remember it was very noticeable at about 1500rpm when loading the engine from 1000rpm in a high gear.

I could also sense a misfire/vibration with car in neutral, gradually increasing rpm.

the flyin' scotsman

thx again John.

Im going back in to see if a swab was left and replace the FIs with my OEM Porsche units (replaced with new Ford 4 hole pintle) which were reconditioned and ran in my car flawlessly.

be back with an update report Sunday

the flyin' scotsman

since my last post the owner decided to replace the 'refreshed' injectors with new.

the project was going well until we dicovered a missing pintle cap which led to another decision to pull the intake again, retireve the stray cap, inspect and put together..............all done.

the car fired first time after fuel pressure reached, its perfectly smooth at various rpm, idles perfect.

A road test was not possible due to negative ambient and frozen/ice covered road outside the garage but spring will be the real tell tale.

Not sure if I mentioned previous but when this car was initially started after the intake r&r it shook and vibrated with the 'refreshed' injectors which went away only to re-appear when on the road.

Many thx to Roger for sourcing the new injectors and to everyones inputs. I'll be back to report how th road test goes

heinrich

Malcolm I had an S4 I basically gave away once because after a large overhaul of small bits including intake, I could not get it to take load, and was just tired of working on it .... turned out it was an air leak under the intake.

Bill Ball

You found the pintle cap? I worked on a car where the engine ate 5 of them with no ill effects. They were gone. Decided to leave them off. They are not necessary.

Hope you found the issue. Being engine speed-related limited the hunt somewhat and it looks like you found it.

the flyin' scotsman

ok............we had +10c weather today, unbelievable for Jan in Alberta so the owner had the car out.

I'm very glad to report the new injectors (yes they are new) cured the horrendous vibration issues after the intake rebuild.

We can now move onto to other projects

heinrich

Yay!

GlennD

Congrats Malcolm. Great to see this issue has finally been put to rest.

Glenn

928mac

+ 1 on that Malcolm

John Speake

Glad to hear that new injectors fixed the problem, Malcolm !

the flyin' scotsman

thx all.

I want to assure everyone that the vibration problem was so bad I had convinced myself that somehow the driveline had failed even though all that was done was remove the pressure from the front flex plate and service the auto transmission (oil, filter etc).

Accepting that it was possible, although I thought very remote, that somehow the intake refresh was possibly responsible for the bad vibes was just as difficult to fathom but in the end it was a part failure that gave the under load issues.

I dont know how many of the eight refurbished injectors had problems but would suggest it was a few and can only surmise that the engine load is real high just below 3k rpm and thats why the vibes were so bad at that frequency.

The problem is now fully resolved and hope this thread helps others in their own repairs.

cheers

Mrmerlin

glad the new injectors fixed your issue I had an 86 in here thats also was doing funny things once it warmed up.
sent the new looking injectors to Witchunter and got a cal hey these are all junk.
I got another set of Ford Denso injectors off Ebay and it was plug and play,
The Denso are Bosch copies and appear to work fine

ROG100

Malcolm,
We sent the injectors back and had them tested and all proved good - no idea what changed.
We powered them here before sending them back and all worked but I wanted them flow tested.
Maybe as you say at certian load levels one or more caused an issue. We won't be using them to be safe.
I am glad the new ones worked.
Roger

the flyin' scotsman

Interesting Roger but other than installing them on another car I wouldnt know what else to suggest.

As stated above we installed the new injectors after the intake was removed and re-installed to retrieve the awol pintle cap. Nothing was done to the intake or any other parts replaced.

BTW.....the brand new injectors are works of art

Its also interesting that my personal car runs perfectly on refurbished 4 hole injectors...........go figure.