17 replies to this topic

[Ripple]

I had a full stainless system fitted to my 97 MPI recently with decat pipe, since this has been on I get a very heavy pop and crackle anytime I take my foot off the accelerator and let the engine take the strain. I assume this is unburnt fuel getting into the exhaust but I am little concerned about damage to the manifold (as this seems to be where it's burning) and not as much but fuel consumption obviously has to be higher than it should be as I'm burning fuel in the pipework rather the the engine

Any ideas of how to reduce/fix this and how concerned I should be about any damage being caused

Ta in advance guys

[Down&Out]

Its not blowing is it?

Mine used to pop on overrun when the exhaust blew, but then again, the popping could be due to lack of backpressure (in my case, due to the blowing at the manifold)

As you've fitted a decat maybe you've reduced backpressure and thus the popping.

I might be wrong, but thats my logical spin on things!

[6joshh6]

It could be a problem with your exhaust manifold joint; I had a dodgy seal between the two pipes and it made it pop and bang loads so it might be worth going over the manifold (especially the Y piece) and checking for leaks.

[Fossy313]

I have a 97 mpi mate and I fitted a full decat system too, it pops like crazy but I haven't found any leaks or anything so I have left it...

Edited by Fossy313, 17 July 2013 - 03:01 PM.

[Fossy313]

Ripple there is loads on the tinterweb about this, it's a common thing with the mpi and a larger bore exhaust as log as u rule out no leaks, it's just unburnt fuel, it's a common occurrence with minis, mine does it and it seems like loads of other people's have it, it's more common in mpis and with the decat pipe fitted none of the unburnt fuel popping is silenced so it sounds louder........I love mine when it pops haha

Edited by Fossy313, 18 July 2013 - 07:08 AM.

[Ripple]

thx all...

 

Fossy, thats just what i wanted to hear, there's no blow anywhere and just wanted to know if any others had the same problems

[Fossy313]

Jesus mate sorry I just re read that and the text is awful, stupid predicted text on my phone..

[Ripple]

Lol... Damn you autocorrect!!!

Could have been worse

http://www.damnyouau...y/best-of-dyac/

[jaydee]

Thats normal and wont damage you manifold.

[Minimad100]

My 1999 mpi with LCB and big bore exhaust is the same too!! Wakes you up in the mornings lol

[Gr4h4m]

Popping on over ru. Is normally a lean condition iirc. Google it.

[Fossy313]

It's normally a lean mixture however you can't do anything to change the mpi s fuel or timing as its controlled by the unchangeable ecu, as long as their are no leas its just a bit of unhurt fuel causing a reaction with oxygen, the decat pipe added to this due to having no cat. Just double check for leaks but most mpi s with a big bore exhaust will pop due to having injectors, being the main reason why carbs don't do it as much.

[Fossy313]

Lol... Damn you autocorrect!!!
Could have been worse
http://www.damnyouau...y/best-of-dyac/

Hahaha that made me chuckle!!

[minimaxie]

I thought that was normal on an MPi? They tend to overun and pop quite a bit, if you're worried, check all the sensors such as the vacuum, idle air control valve, lambdor sensor etc. Check for leaks all over but to me that sounds normal, mine does it very rarely with a standard pea shooter and CAT still fitted lol

[Fossy313]

Mine pops like crazy!! But I have got a big bore decated maniflow full system

Edited by Fossy313, 28 July 2013 - 06:28 AM.