Fuel cut before boost

suby25 · Post by **suby25** » Mon Mar 06, 2006 7:15 am

I have a USDM 95 Impreza L with the EJ22T Legacy Sport Sedan motor swap. I've been experiencing a problem lately where the motor will cut fuel when I reach zero vacuum pressure and begin to build boost. The CEL comes on immediately when I start the car, and I am not able to generate any boost. The throttle has quite a delayed response and sometimes won't respond at all. I'm running the TD04 WRX turbo as well as stock WRX intercooler, 3" TBE and gutted stock uppipe. Any idea what might be causing this problem? It feels like the ECU is also in limp mode, and sometimes will not rev above 4500RPMs. I'm going to try to figure out what CEL's I'm getting, but has anyone experience this problem?

vrg3 · Post by **vrg3** » Mon Mar 06, 2006 7:37 am

You neglected to say what ECU you're using.

Assuming it's an EJ22T ECU, the trouble code that you pull will probably tell you to check out the pressure sensing stuff or the boost control solenoid.

Binford · Post by **Binford** » Mon Mar 06, 2006 7:42 am

Yes, I've experienced it. I'm not sure what I did to fix it though. I think my ECU just took awhile to get used to my new setup consisting of the TD04 and topmount. I suggest checking over all vacuum lines, specifically related to the map sensor/boost controller. Are you using the stock boost controller, or something else? After doing a good visual check, reset your computer and see what happens. Let us know what codes you get, and go from there.

Binford · Post by **Binford** » Mon Mar 06, 2006 7:43 am

Damn I type slow!

suby25 · Post by **suby25** » Mon Mar 06, 2006 7:43 am

Sorry, I am using the EJ22T ECU. I will have to pull the codes and see what kind of problems I'm seeing.

suby25 · Post by **suby25** » Mon Mar 06, 2006 7:48 am

Wow, you guys post before I even got my reply up. I'm using the stock boost controller to my knowledge, I just purchased the car last weekend, so I've been looking it over and replacing parts that are faulty.

I'll reset my ECU and see what happens. The ECU seemed to learn around the new turbo after a while, since I think it was a fluke that we messed around the with throttle postion sensor and it happened to work. We disconnected the ECU later to weld on the car and after we reconnected it, it started to have the same problems as before. Hopefully we can figure it out. Thanks for the replies, I appreciate the help.

vrg3 · Post by **vrg3** » Mon Mar 06, 2006 8:20 am

What were the trouble codes?

legacy92ej22t · Post by **legacy92ej22t** » Mon Mar 06, 2006 2:40 pm

Sounds like the MAP sensor. If the MAP sensor doesn't get a signal or is bad, you'll have those exact symptoms.

92whitelegacy · Post by **92whitelegacy** » Mon Mar 06, 2006 7:14 pm

When i wired in my FCD that happend to me. Simply because i didnt get a good connection on the 12+to MAP wire or somthing. I cant believe you can even drive it thats crazy....if i tried to give it ANY throttle it would just bog and die. yep. Just my .02$

dzx · Post by **dzx** » Mon Mar 06, 2006 11:46 pm

Is the MAP sensor the sensor next to the boost control solenoid? I've been having my CEL come on randomly and when its on, if I roll across 0psi it starts bucking.

vrg3 · Post by **vrg3** » Tue Mar 07, 2006 12:59 am

Yes. Look at the picture at the top of this page:

http://www.graphics.cornell.edu/~v/chrysler_map/

dzx · Post by **dzx** » Tue Mar 07, 2006 1:23 am

wow, 400 dollars. Thanks Vikash.

dzx · Post by **dzx** » Tue Mar 07, 2006 5:09 am

I guess one more question, should the CEL come on when you unplug the pressure exchange solenoid?

vrg3 · Post by **vrg3** » Tue Mar 07, 2006 5:22 am

Yes. The same code, in fact, as for when the pressure sensor is faulty.

dzx · Post by **dzx** » Tue Mar 07, 2006 6:06 am

I unplugged it and the CEL didn't come on....weird.

vrg3 · Post by **vrg3** » Tue Mar 07, 2006 6:15 am

Yes, weird.

suby25 · Post by **suby25** » Tue Mar 07, 2006 6:29 am

We replaced the aftermarket Perrin BOV today with the stock bypass valve and plumbed a return line back into the intake, since it was lacking one before. I disconnected the battery for an hour or two and upon startup the CEL came on almost instantly. My guess is there is a sensor that has gone bad and triggers the CEL to come on, I just don't know which one. I'm going to the dealership tomorrow to have them pull codes for me and hopefully clear them at the same time.

suby25 · Post by **suby25** » Tue Mar 07, 2006 6:32 am

I forgot to mention the hose on the IAC was missing when I got the car, and we blocked it off tonight.... would this pose a problem?

vrg3 · Post by **vrg3** » Tue Mar 07, 2006 6:45 am

You can pull the codes yourself. Don't pay a dealer to do it.

The big hose was missing? And the engine was still able to idle? And it's still able to idle with it blocked off? That's all surprising to me... I would think you'd need it to be plumbed right for it to work at all.

suby25 · Post by **suby25** » Tue Mar 07, 2006 7:02 am

When I originally got the car, the bearing on the IAC (what I believe to be the IAC) was filled with crap so some air would pass by, but the majority of it would be blocked.... I put a hose on it with a cap on the end and it idles just like it did before when it was open. I don't know what its supposed to look like, but its located on the throttle body above the TPS. I'm not positive it is the stock Legacy Turbo TB.....

vrg3 · Post by **vrg3** » Tue Mar 07, 2006 7:23 am

Oh. That's not the EJ22 throttle body.

I didn't know the TB-integrated IAC valves even had separate inlet hoses.

Is this a small hose? Like 7.5mm? Maybe it's a coolant line?

What intake manifold do you have?

Is there a device bolted to the intake manifold below the PCV valve?

How many wires are on your TPS?

Who did this engine swap?

And what are the trouble codes?

dzx · Post by **dzx** » Tue Mar 07, 2006 7:42 am

are you talking about the purge cannister solenoid line?

legacy92ej22t · Post by **legacy92ej22t** » Tue Mar 07, 2006 1:33 pm

suby25 wrote: My guess is there is a sensor that has gone bad and triggers the CEL to come on, I just don't know which one.

legacy92ej22t wrote:Sounds like the MAP sensor. If the MAP sensor doesn't get a signal or is bad, you'll have those exact symptoms.

suby25 · Post by **suby25** » Tue Mar 07, 2006 4:18 pm

What I have been referring to as the IAC is located on the top of the throttle body, slightly closer to the firewall. There is a small rod coming out of it that goes through a bearing and can be adjusted to open, closed, or a mix. There was no hose coming off it when I bought the car. The intake manifold is black, I don't know if it is stock or not. I don't know anything about the car, or who did the swap. Damn.... I guess this puts me in a hard place.

I took it to the dealership and they said they could not pull a code. I don't know how that is even possible, so.... I guess I'm left with a manual code search.

vrg3 · Post by **vrg3** » Tue Mar 07, 2006 4:42 pm

Are you reading what people are saying to you? We'd like to help you but I don't feel like you're doing your part.

Matt has already said that it could be your pressure sensor. At least take a quick glance at the sensor and its electrical and vacuum connections and let us know what you find.

I said that you can pull the codes yourself. Please, pull the codes and tell us what you find. Here, I'll even give you links to the info you need:
http://www.surrealmirage.com/subaru/engine.html
http://bbs.legacycentral.org/viewtopic. ... 097#112097

Please, tell me how many wires are on your throttle position sensor.

And please tell me if there is a device bolted to the intake manifold just underneath the PCV valve.

Also, please, take some pictures for us. It's hard to know what's going on just from your description.

Please!

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Fuel cut before boost

Fuel cut before boost