please help!big mhi 16G...

[jen_cairo]

i need input please. i recently drove my car for the first time after installing my mods which are all listed in my profile. the problem is my boost starts to hit about 4k then about 4200k i hear a pretty loud noise as if it was backfiring or something. i do have my mbc controller turned all the way down cause i have No fuel upgrades at this time and no cat back. it should be in the mail anyday now and im in the process of looking for a good priced safc. i was just wondering if any one has advice. the last thing i wana do is blow my engine or turbo. thanks

 

[-TunedDSM-]

How much boost are you running? According to your profile you have an external wastegate so you shouldn't be boost creeping. What happens when it backfires, does it hesitate or feel like you hit a brick wall? I would check for boost/vacuum leaks and change out the spark plugs.

Most of all, stop beating on the car when you don't have the proper fuel mods. Try removing the MBC and running a vacuum line directly from a boost source to the wastegate, don't tee the BOV line.

 

[95gst16g]

Spooling that late on that turbo is odd....You might have a exhaust leak check the e manifold to head and the manifold to turbo and make sure they arent leaking.

 

[jen_cairo]

How much boost are you running? According to your profile you have an external wastegate so you shouldn't be boost creeping. What happens when it backfires, does it hesitate or feel like you hit a brick wall? I would check for boost/vacuum leaks and change out the spark plugs.

Most of all, stop beating on the car when you don't have the proper fuel mods. Try removing the MBC and running a vacuum line directly from a boost source to the wastegate, don't tee the BOV line.

i have new plugs and wires. it doeS hesitate and sounds like a gun. i wouldnt call 4200k runin it hard. i havnt drove it since.

 

[95gst16g]

How much boost?Its probably fuel cut.Do what he ^^^said and run a vacume line from the j pipe/compressor housing to the wastegate actuator.

 

[jen_cairo]

Spooling that late on that turbo is odd....You might have a exhaust leak check the e manifold to head and the manifold to turbo and make sure they arent leaking.

i retighten the mani. but where it bolts to my turbo i had to put thin nuts on the studs bc my sfp mani. was not very thought out when they made it.

 

[95gst16g]

I dont really get what you mean by thin nuts.Regardless you have to make sure that they are tight or you will have a leak.

 

[jen_cairo]

How much boost?Its probably fuel cut.Do what he ^^^said and run a vacume line from the j pipe/compressor housing to the wastegate actuator.

i dont run my vacuum to either is the intake manifold ok? and im currently runing about 10 to 12psi.

 

[95gst16g]

You should deffenatly get a nipple on the compressor housing or the j pipe.But if your only running 10-12psi then it shouldnt be fuel cut.I ran 15psi or 16psi on my small 16g when I first got it and back then I was all stock fuel wise.

 

[jen_cairo]

You should deffenatly get a nipple on the compressor housing or the j pipe.But if your only running 10-12psi then it shouldnt be fuel cut.I ran 15psi or 16psi on my small 16g when I first got it and back then I was all stock fuel wise.

that was my biggest ? do i need fuel upgrades for my car to run rite with my mods?

 

[95gst16g]

It would be a good idea to have a wideband and something to tune with and log with but I got away with running my small 16g on all stock fuel system and motor for a few months until I could afford the pump injectors,and dsmlink.I wouldnt recomend it but It worked.I never really beat on the car back then when it was like that.

 

[SpeedAddict62]

I originally bought my car with a small 16G and I was completely unaware of it at the time. The car was bone stock otherwise and it ran just fine, aside from the fact that it spooled a tiny bit slower than a 14B. That was with stock boost, stock exhaust, etc. As soon as I put on a full 3", I started creeping to 15 psi and the extra flow was too much for the stock fuel system. The fuel pump was the weakest link, then the injectors. Having an external wastegate is a distinct advantage, since you can keep boost down to stock levels. However, the fuel system on these cars were simply not designed for anything above stock power levels, and your symptoms do sound like running out of fuel (cutting out, loss of power, popping from the exhaust).

What is the spring pressure of your wastegate? Any vacuum source is fine, as long as it sees boost pressure. My advice is to keep out of boost until you figure out what the problem is. Your spool is way too late for a 16G. You need to test for boost leaks and look carefully for exhaust leaks as well.

Don't mess with a piggyback, they aren't worth the time or money. Today, there are plenty of options available that offer more potential, such as flashable 98/99 2g ECUs and Evo ECUs. Look into them before you go searching for a piggyback.

 

[jen_cairo]

I originally bought my car with a small 16G and I was completely unaware of it at the time. The car was bone stock otherwise and it ran just fine, aside from the fact that it spooled a tiny bit slower than a 14B. That was with stock boost, stock exhaust, etc. As soon as I put on a full 3", I started creeping to 15 psi and the extra flow was too much for the stock fuel system. The fuel pump was the weakest link, then the injectors. Having an external wastegate is a distinct advantage, since you can keep boost down to stock levels. However, the fuel system on these cars were simply not designed for anything above stock power levels, and your symptoms do sound like running out of fuel (cutting out, loss of power, popping from the exhaust).

What is the spring pressure of your wastegate? Any vacuum source is fine, as long as it sees boost pressure. My advice is to keep out of boost until you figure out what the problem is. Your spool is way too late for a 16G. You need to test for boost leaks and look carefully for exhaust leaks as well.

Don't mess with a piggyback, they aren't worth the time or money. Today, there are plenty of options available that offer more potential, such as flashable 98/99 2g ECUs and Evo ECUs. Look into them before you go searching for a piggyback.

thats very interesting to know thanks for the info. what do u think bout the safc?and to be honest i never looked at the wg spring.

 

[airmail96]

Honestly, I don't see the point in a SAFC if your running the stock injectors if I am thinknig correctly the stock ecu controls them pretty well.

 

[SpeedAddict62]

The SAFC is a piggyback, so I don't like it . IMHO, piggybacks are a bandaid fix. They work by lying to the ECU about airflow to affect a change in the amount of fuel delivered. It works in theory, but the problem is that timing is also based off of airflow in the ECU code. If you lie about airflow, you change the fuel demand and timing simultaneously. If you want to lean it out, the piggyback says there is less airflow than there really is. You get less fuel, and generally more spark advance. When you're compensating for larger injectors and starting to make some power, you'll keep getting more timing where you don't want it, and too much timing leads to knock.

Airmail: An SAFC could be used with stock injectors if you were to lean it out some, since the stock ECU code is overly rich (9.5:1 or so). However, again, it isn't the best solution, and really shouldn't be done without a wideband. There isn't a reason not to have one, especially since a LC1 can be had for $150.

The reason I asked about your wastegate spring is because I wanted to know the lowest possible boost you could run (with the MBC removed). On an external wastegate, you can't run anything less than the spring pressure. Because you're having problems and you aren't sure what is going on yet, it is best to keep boost as low as possible (or not boost at all) until you know what the problem is.

 

[jen_cairo]

I decided to get an safc II which is on the way along with 550cc rc injectors and a 190 walbro.
Im gonna install everything when it gets here and then go from there.