Help required from owners of “De pre-catted” cars
Discussion
I recently replaced the standard header pipes with ACT stainless pipes without pre-cats and fitted with reversing cones. Since fitting them I get a light-grey haze (which I assume is fuel and carbon) discolouring the rear end of the car after only 50-100 miles of driving. Assuming this was not normal I had the car set-up by Mark Adams on Austec’s rolling road, at the same time fitting Bosch fuel injectors. Whilst this did increase torque tremendously (and hurt my wallet accordingly) 
I still have the hazing problem 
I don’t want to just put up with it (so no comments like just wash it off). It’s so bad that the entire rear end of the Griffith was covered yesterday evening after just a round trip of 40 miles to the local Berks TVRCC meet.
So, advice please chaps - is this normal? Do other owners of cars without pre-cats experience this? If it’s not normal does anyone have any idea what the problem is and how I might resolve it?
I would really appreciate your thoughts and comments.
Cheers Rich…
I still have the hazing problem I don’t want to just put up with it (so no comments like just wash it off). It’s so bad that the entire rear end of the Griffith was covered yesterday evening after just a round trip of 40 miles to the local Berks TVRCC meet.
So, advice please chaps - is this normal? Do other owners of cars without pre-cats experience this? If it’s not normal does anyone have any idea what the problem is and how I might resolve it?
I would really appreciate your thoughts and comments.
Cheers Rich…
Nope same fuel, nothing changed from usual except of course the injectors and a morning on the rolling road with Mark. Obviously he is aware of the issue because that's why he originally had it for a "fettle" after fitting the pipes. I was just hoping to get some additional ideas before I spoke to him again. Rich...
Rich...Rich
Did you put this question to Mark when he did his fettling? I'd imagine combustion'd be totally spot-on after leaving his hands.
My engine modification list is almost identical to yours. Like you, I not long ago, fitted the same manifolds, albeit in mild steel, but don't appear to be witnessing your symptoms (dirty rear end
). Having had my emissions checked recently I find that they've become marginally enrichened: just over the MOT limit at idle and barely in limit at 3000 rpm. I can't necessarily ascribe this to the manifolds however as there may be a malfunction yet to be diagnosed. Despite this, my Griff maintains the cleanest/shiniest butt goin' (soz ). I'm sure that Tim Lamont had not too long ago replied to a post ref' fuelling after fitting these manifolds; it may even have been your post!
Do you have any pictures to add as an aid to diagnosis?
Edit: forget the first para', was a bit slow in hitting the Send Button
>> Edited by 2Munkys on Wednesday 18th May 17:07
Did you put this question to Mark when he did his fettling? I'd imagine combustion'd be totally spot-on after leaving his hands.
My engine modification list is almost identical to yours. Like you, I not long ago, fitted the same manifolds, albeit in mild steel, but don't appear to be witnessing your symptoms (dirty rear end
). Having had my emissions checked recently I find that they've become marginally enrichened: just over the MOT limit at idle and barely in limit at 3000 rpm. I can't necessarily ascribe this to the manifolds however as there may be a malfunction yet to be diagnosed. Despite this, my Griff maintains the cleanest/shiniest butt goin' (soz ). I'm sure that Tim Lamont had not too long ago replied to a post ref' fuelling after fitting these manifolds; it may even have been your post! Do you have any pictures to add as an aid to diagnosis?
Edit: forget the first para', was a bit slow in hitting the Send Button
>> Edited by 2Munkys on Wednesday 18th May 17:07
If it was over fuelling significantly, you would notice the fuel consumtion get worse. What sort of residue is it? Mine runs *very* rich and I get a thick black coating over the back of the car. It's very sticky and doesn't just wipe off (unless you are walking past it with clean clothes on 
).
).Yes I did discuss it with Mark and indeed showed it to him because the rear was covered after the drive down to Gatwick. Obviously when I left Austec after the morning on the RR mark was pretty certain it was spot on. Trouble is that I would have needed to have driven for 50 miles to discover if the issue was sorted, must confess I just assumed that with the new injectors and 3 hours on the RR it would be fine. Pretty disappointed to see that there is no change. I expect Tim's response was to my post 4 weeks ago. Oh and the haze is a very pale grey (almost white) and can easily be wiped off so where I opened the boot last night to put the roof on there are finger marks.
So no one else with a de-pre-catted car has this issue?
So no one else with a de-pre-catted car has this issue?
I aknowledge that you tie this problem in with the fitting of new manifolds Rich, but is it possible that these are not combustion products? Despite its appearance, could there be leakage from under the car and the generated turbulance from a drive create that which you are seeing: fuel pump/filter? Just a thought!
>> Edited by 2Munkys on Wednesday 18th May 18:17
>> Edited by 2Munkys on Wednesday 18th May 18:17
rich,
if its dry (powdery) it won't be fueling/oil etc.
a "haze" indicates dry to me, which says cat brake up (which IS grey) or silencers packing - unlikely, as normally carboned up.
its relatively easy to remove the Y-piece which is where the problem will be seen (as pre-cats have gone). good chance is a bit of pre-cat broken of either before or during de-cat process, which is sitting on the main cat, disintegrateing and being blown out by pressure.
if your unlucky its main cat brake up!
blockages like this steal power so you COULD end up with another 10bhp!
fingers crossed.
>> Edited by Guillotine on Wednesday 18th May 18:58
if its dry (powdery) it won't be fueling/oil etc.
a "haze" indicates dry to me, which says cat brake up (which IS grey) or silencers packing - unlikely, as normally carboned up.
its relatively easy to remove the Y-piece which is where the problem will be seen (as pre-cats have gone). good chance is a bit of pre-cat broken of either before or during de-cat process, which is sitting on the main cat, disintegrateing and being blown out by pressure.
if your unlucky its main cat brake up!
blockages like this steal power so you COULD end up with another 10bhp!
fingers crossed.
>> Edited by Guillotine on Wednesday 18th May 18:58
I know this may be a daft answer BUT when removing your cats this allows the other eliments to come through ie OIL er mine was running on std 20/50 multigrade and when I went out for a blast their was a milkie white film all over the rear of the car, However now on fully sin this has gone.
Just a thought
Steve....
Just a thought
Steve....
I hammered my pre cats out, must be two years ago and do not have such problems. There is a "film" that needs polishing off every now and again, but then i have had that on most,if not all cars i have had. Maybe you could buy some of those nice chrome exhaust finishers to direct the "smoke" down, only seen them for Austin eleven hundreds though ! Ah my first road car.
Guillotine said:Thanks for all the suggestions guys. It seems to me that perhaps I need to take a look inside the Y piece. Thing is that I can't see why there should be anu pre-cat in there becuase I didn't hammer them out I simply replaced the manifolds and when I looked at the old ones (which Tim took away as an exchange) they looked fine.
rich,
if its dry (powdery) it won't be fueling/oil etc.
a "haze" indicates dry to me, which says cat brake up (which IS grey) or silencers packing - unlikely, as normally carboned up.
its relatively easy to remove the Y-piece which is where the problem will be seen (as pre-cats have gone). good chance is a bit of pre-cat broken of either before or during de-cat process, which is sitting on the main cat, disintegrateing and being blown out by pressure.
if your unlucky its main cat brake up!
blockages like this steal power so you COULD end up with another 10bhp!
fingers crossed.
I'm in a real quandry as i don't really want to spend another grand on the rolling road! But I must get it fixed.
Rich...
stesrg said:This sounds interesting
I know this may be a daft answer BUT when removing your cats this allows the other eliments to come through ie OIL er mine was running on std 20/50 multigrade and when I went out for a blast their was a milkie white film all over the rear of the car, However now on fully sin this has gone.
Just a thought
Steve....
.I'd be surprised if your cat was breaking up,as Mark would have picked this up at the rr session surely?What type of oil are you using,and does it use much?coolant loss?On my last griff i had my pre-cats removed and didnt get anything like this.For the record,i was also using fully synthetic oil(mobil 1).Good luck anyway,hope it doesnt cost too much to sort.Just for the record, i fitted a pair of de-catted std manifolds from Tim @ ACT a couple of months ago. No deposits noticed on my rear 
Incidentaly if there was an oil or coolant leak that was being deposited on the rear through turbulance there would surely be enough left underneath to drip on the floor. I would advise looking for signs of a leak on the ground when you move your car.
Incidentaly if there was an oil or coolant leak that was being deposited on the rear through turbulance there would surely be enough left underneath to drip on the floor. I would advise looking for signs of a leak on the ground when you move your car.
mongoose said:Oil is Mobil 1 Motorsport. And doesn't much anyway, approx 1/2 ltr per 1,000 miles. Coolant very little say about an inch in the tank every couple of months. There is a slight oil leak from the sump area but that's a black oily drip not a grey haze??? Rich...
I know this may be a daft answer BUT when removing your cats this allows the other eliments to come through ie OIL er mine was running on std 20/50 multigrade and when I went out for a blast their was a milkie white film all over the rear of the car, However now on fully sin this has gone.
Just a thought
Steve....
This sounds interesting
Hi Rich,
Just posted a thread up with exactly the same question (now removed), didn't realise this was here. I'm getting a greyish mist on the back of my car. This has only just started happening and seems to wipe off okay but is frustrating.
A mate followed me the other day and said he didn't notice any smoke or tell tale signs from the exhaust.
Mine doesn't have any precats but still has the main cat in. Any thoughts anyone?
Cheers,
Graham
>> Edited by Graham B on Thursday 19th May 17:30
Just posted a thread up with exactly the same question (now removed), didn't realise this was here. I'm getting a greyish mist on the back of my car. This has only just started happening and seems to wipe off okay but is frustrating.
A mate followed me the other day and said he didn't notice any smoke or tell tale signs from the exhaust.
Mine doesn't have any precats but still has the main cat in. Any thoughts anyone?
Cheers,
Graham
>> Edited by Graham B on Thursday 19th May 17:30
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