What happens when injectos are to big

[James]

I recently had to buy new injectors an went up from stock 450s to 550s because they were so close in price. Most of my searching told me this would probably be just fine, but a 2g MAF would make it better.


After putting them in today the car bogs and is a little sluggish at WOT, it seems to drive fine without getting into boost though. Do you think it's my 1g MAF causing it? I had zero boost leaks prior to installing them today but I'll double check that tomorrow

Also: new injectors solved my misfire and bad idle :thumbs up:

 

[Barnes]

You have to compensate for larger injectors! The reason your car is running poorly is because you are now running much richer. Unless you compensate with a key diver chip, dsmlink,AFC, etc etc your car will NOT run properly.

 

[James]

I would say that 99% of everything I read said that 550s would be fine with a 2g MAF and 5speed ECU.

 

[dsm10o0]

550cc are fine on stock ecu and maf. Ran one for couple years without issues.

You probably got something bigger. What kind injectors you got?

 

[turbowop]

550's are far from fine on a stock maf and ecu. Even with a 2gMaf, it's not ideal without an SAFC to fine tune it. Or if you want it to run like sh*t and be slow, by all mean, do what you want... /ubbthreads/images/graemlins/rofl.gif

 

[Jason G.]

+1

 

[VR_IV_MR]

do yourself a huge favor before you destroy your engine. buy ecmlink and an oil pressure gauge. Looking at the $700 price tag, I didn't want to at first. That is until I had to rebuild my block two times. And I am not even talking about only your injector compensation. These 2 things will prevent many potential problems and help you diagnose it as well.

 

[James]

Picking up a SAFC, 2g MAF, and another logging setup.

But I don't have a 2g Intake pipe, I'll have to rig it up somehow till my next paycheck.

 

[JNR]

Also, remember different injectors have different 'timing' (whatever the term is) and so on, so just because a Denso 550 may work, an FIC 550 may not on a stock ECU, plus different spray patterns, although don't think that'd be such an issue. A final thing about FIC's and not too many seem to have issues with this, but they are shorter than Denso's and the right way to do it is to shorten your isolators so they seat the same into the head. It's only like 1/32" difference and many people have been fine not doing this, but when I compared the two this was the result (I went from Denso 550 to FIC 650 and back to Denso 720; each time with a chip made for either of them).

 

[James]

Thanks JnR that's a good point.

Here's my rigging up idea as a temp fix (BIG THANKS TO TRANSPARENTDSM for sending me a free 2g intake)...

Please no flaming about how redneck ghetto it is, I know, but it should work in theory correct?

Electrical tape ran left to right from pipe to MAF all the way around, the around the entire thing in the other direction

 

[Ian M]

I'm not totally sure what you are talking about doing but if it's what I think it is-yeah,it'll work great until the tape gets sucked shut then into the turbo. /ubbthreads/images/graemlins/rofl.gif

You'd be better off going to lowes and getting some "3 pvc and fernco couplers.

 

[James]

Bam I phone apps haha. If I can find a coupler that's the oval shape of the MAF then yea I'll go do that lol

 

[Ian M]

The "3 fernco couplers will stretch over the MAF and they are cheap,don't do tape.

 

[JNR]

PVC is not a good material to use under the hood, fwiw...it gets brittle too easy and especially never use it under pressure; well a turbo doesn't put out a lot of pressure like an air compressor does (big no no on PVC unless you want it to blow up, lol), strictly speaking about pressure part; of course inlet is not under pressure and doesn't see vacuum like the manifold I imagine. Still, there is heat there. Instead, if you're going to do home depot special, least get the ABS plastic (works fine and will last). Those fernco rubber couplers work OK and I've used them for air intakes, although don't think I would for the pressure side.

 

[James]

JNR it's only going to be used for a few days, (as long as shipping takes till I get the 2g intake from transparent)

I'll browse the store and see what I can find, I just need to make it drivable to get to work and back.

 

[JNR]

Oh, OK...then you should be alright for temporary then (PVC), although ABS or the like isn't that much more and also has alot of fittings available...bring a tape measure with you though, since some is pipe (3" = 3.50 OD) and some tube sizes 3" = 3.00 OD), etc.

 

[James]

I see, I'll probably bring the MAF in the store with me and make sure it bolts up fine.

 

[Ian M]

Quoting JNR:
PVC is not a good material to use under the hood, fwiw...it gets brittle too easy and especially never use it under pressure; well a turbo doesn't put out a lot of pressure like an air compressor does (big no no on PVC unless you want it to blow up, lol), strictly speaking about pressure part; of course inlet is not under pressure and doesn't see vacuum like the manifold I imagine. Still, there is heat there. Instead, if you're going to do home depot special, least get the ABS plastic (works fine and will last). Those fernco rubber couplers work OK and I've used them for air intakes, although don't think I would for the pressure side.



Yeah,that's what I meant..the ABS (the black stuff). /ubbthreads/images/graemlins/wink.gif It looks gangster too,but better than tape. I know guys who have run ABS intakes for years.

I second those Fernco couplers work fine for a intake (everybody I know including myself has used them on 2g MAF setups),but not on the boost side. A freind of mine had a Merkur XR4ti about 15 years ago,being cheap and a turbo newbie used it for couplers on a starquest IC setup. You could just free rev it and watch the coupler by the TB expand like a balloon. /ubbthreads/images/graemlins/rofl.gif He blew a few of those apart before going to silicone.

Not only do the Fernco couplers stretch over the oval MAF,they have to be squeezed down with the clamp to a fit a "3 pipe but it will work. They are thick rubber but pliable.

 

[JNR]

LOL, yeah they are pretty flexible! I've also used them a few times in the past on intake tracts just fine, but always turn them around so all that text doesn't show, ha ha.

As for the ABS, I like using it also and it comes out good if you chop off the "female" part of the fitting(s), although not a lot of choice in joining pieces together otherwise w/o using couplers. Once you paint it, looks pretty good actually, but the only thing I don't like about it is that it's pretty thick, since it only seems to come in sch 40 (.216" wall on 3" pipe), but it's not that heavy and doesn't act as aheat sink like metal can.

For the galant though, I ended up using a 4" FP tube assembly that I welded on some bungs (tubes w/beads) for the recirc and emissions/PCV breather lines and repainted and it came out pretty good...Prior to that made a 3" tube out of exhaust pipe (found the perfect piece that was already mandrel bent) and added some beads and a tube for recirc, but it was a little too small for my turbo, so I'll probably sell it soon.

 

[James]

waiting ot hear back from the maf and logger sellers. then its off to home depot, then its reading time to lear how to wire the 2g into the 1g