turbo problem, please help!

[deeyonthebrit]

Ok, so i bought a 1995 turbo 240 this past weekend and everything is great except there's a slight problem. When i push down the throttle a good amount there are loud popping noises from the exhaust and i significantly lose boost.

I have been informed that the problem is that im not getting enough gas to the engine in comparrison to air and therefore detonating, thanks to the turbo : ). The turbo is set @ 8psi, and the previous owner upgraded the injectors to venom 450cc's. I took the car to the performance shop and he said i needed 550cc injectors to fix the problem...

I've been reading all over the internet and the majority of the posts say that 450cc injectors are just fine for 8 psi; however, a new upgraded fuel pump is needed (it's also significantly cheaper than 550cc injectors).

I was wondering what you guys thought...Would it be better to get the 550cc injectors? Or simply upgrade the fuel pump and keep the 450cc venoms?

edit: there is also an Apexi AFC Neo Air Fuel Controller in the car...how would this help my situation? sorry again, im new...

All input is greatly appreciated. Also i am new to 240's and especially turbos...So, sorry for my lack of knowledge, but i got to learn somewhere : ).
Modified by deeyonthebrit at 11:54 PM 5/6/2008

[Ilvemynissan]

Well what kind of motor is it???? If it's an SR, RB, or CA 8 PSI is fine. A turbo KA on the other hand I have no Idea but if it already has 450cc injectors it should be fine. I would say it's the fuel pump but i'm not certain, also check the spark plugs gap that also could be a problem I believe, but if it's not getting enough fuel then it's somthing else.

And Welcome to NICO

[deeyonthebrit]

Oh, lol, i forgot to mention that it's a KA24DE.

Thanks mate, its a great site!

[Ilvemynissan]

Yah i'm not too familiar with the KA's but try searching around on this site, there's A LOT of useful information here.

[assassin7420]

IT could just be a bad tune. Put a wideband o2 in the car or run it on a pipe sniffer.

[480sx]

Whoever told you that you needed bigger injectors to fix your problem was full of crap. I would be real hesitant to ever take a car back there if i were you.

Its POSSIBLE(not likely) that the problem could be linked to your fuel pump, but what your describing is not detonation. You really should upgrade to a 255 walbro fuel pump though. Its a necessary thing to have on every boosted 240, the stocker just cant keep up with the demand for fuel.

Have you made sure you dont have a boost leak? Its a simple test, you just pressurize your intercooler system, and intake manifold from the turbo and listen for escaping air. Here, read this link it explains what you need to do.

zerothread?id=113785

Also, if you want some good reading about the engine you have check out this FAQ for the Ka-T.

zerothread/99647

[deeyonthebrit]

If im not getting enough gas to the engine with 450cc injectors, what else would the problem be?

[Ilvemynissan]

Like 480sx said get a Walbro 255 (z32). I have one for my SR and it is fine.

[nrmskate]

My guess would be the fuel pump also, I don't see how bad spark plugs can be an issue with the popping noise you here, the spark plugs just makes the spark to start the car. Like the above said, the Walbro pump is an excellent pump and should solve your problem, if not, just post back here with an update.