So guys I'm in massive need of help. I picked up a 98 maxima SE and decided to hook my old MEVI up to it. Got everything hooked up and now the car runs like crap. Before I put it on the CEL came on P0400 EGR malfunction. So I cleaned the EGR tube while I had the manifold oFf which was completely clogged. Now the light is still on except with a random cylinder misfire, fuel air ratio code, and some auxillary something code. My car was perfectly fine running up until I put the MEVI on, i've installed this same one twice before so I know how to install it. The only thing I can think causing it is a vacuum leak somewhere. I also saw that the nipple by the throttle body on the MEVI sticks straight out while on the USIM it bends up. So could the problem be that the hose adapter I used is causing a leak?? I have no idea what to do and am considering just putting the stock manifold back on. Hopefully you guys can help me out. Or if anyone is in the Delaware area come help me out. Thanks guys.

 

should be the same concept on maximas as well.. but on my 5L mustangs when i would do intake swaps if i was suspect of a vac leak somewhere, i'd take some tb/carb cleaner and spray in the direction of where i thought the leak would be. when the tb/carb cleaner comes in contact with a leak, the idle will fluctuate noticeably.

i know this might not be the answer to your question, but hopefully it gave you some incite to eliminating a vac leak somewhere.

 

if you didnt have these problems prior to install, its going to be a VAC leak, check your hoses; spray some carb cleaner.

 

Hoses all look fine, but i don't even know where I think there is a leak. Should I just randomly spray all hoses and Vacuum related parts? I replaced the throttle body and intake manifold gasket so far. I've been reading it could be the open EGR valve and the vacuum leak causing it so, it's looking like I'll be spending alot of time and money next week.

 

if the egr valve wasn't bad b4 the install, chances are it shouldn't just fail now. it's possible, but unlikely. you can spray all the vac lines, any gaskets you've replaced & anything in the vicinity of where you had your hands in. what's the worse that happens?? You don't find the leak but you have some squeaky clean vac lines and connectors

 

Well it was throwing the EGR code before so it could have possibly been bad before. No real way to tell

 

fwiw, out of the 3 4g's we have here. One 97 SE Stick was throwing a PO400 EGR insufficient flow, the tube was clogged. 170k miles on the car, the egr valves don't usually fail, it's usually the tube gunking up. Let me know if any developments?

 

I cleaned the top of the tube out and where it connects to the intake manifold, both of which were pretty clogged. Come to think of it does the EGR tube have a gasket between it and the manifold, I can't remeber if I saw one. And if it isn't there could that be causing the leak.

 

yes there is one. a metal gasket.

 

Problem most likely solved
Let us know the results!

 

Yea I'm hoping that's what it is because I didn't have one there, although idk what happened to it....it's a special order at my store and parts stores around here so probably won't be able to get one till next week, I'll keep you guys posted though. You think it could cause all those problems?

 

Its a Vaccum leak; yes.

 

So guys replaced the gasket today and disconnected the batery for about 20 mins. Cranked it up it reved up to about 3 grand then leveled back out at 1200. It's running better but, it's still stalling out randomly. I'm thinking probably since I had the battery disconnected it reset the ECU and system driving memory, in which case it'd go back to normal after a few days or a week or so. What do you guys think,

 

20 minutes won't reset the ECU. 12+ hours will. Just clear the codes at the ECU with a baby screwdriver.

Check your spark plugs, seriously. The crap you cleaned out could have have fallen down the tube, then got sucked into the engine and stuck between the ground electrode and the central electrode of the spark plug.

 

I'll have to try that tomorow, I'm hearing like a hissing sort of so I'm still thinking a leak too, but am having next to no luck finding it, I've replaced all of the gaskets. I guess I'm off to replacing all the hoses now too. I'm really starting to get discouraged.

 

When I installed my brand new MEVI I had a leak but I found it. Make sure you double check the EGR tube that's in between the intake manifold and the back firewall. The space is very tight back there, but the back EGR metal tube is bolted in with two bolts and requires a gasket. I am not referencing the EGR unit that sits on top, I am referring to the metal tube that runs from the rear bottom of the upper intake manifold. Simply place your fingers around there and pass your hand around while the car is running to listen for hissing sounds and changes in hissing sounds as you pass your hand.

 

Just retrace your steps. You'll find the leak. Probably too cocky installing this one since you've done others and didn't pay enough attention. I'm sure you'll figure it out.

 

I'm attempting today, so well see what happens I'll keep u guys posted

 

Ok so IACV gasket replaced, sealed up the brake booster hose and valve coming into manifold, which was causing a minor leak, and changed the PCV valve to no avail. When spraying for the vacuum leak, it revs up in idle when you spray under the manifold towards the runners and on top of it on the hose that runs from the PCV valves hoses to the manifold. I'm starting to run out of ideas and hope guys. Taking the manifold off tomorow to see what's going on and give everything another once over

 

Did you replace the main rubber gasket under the MEVI? Did you torque the bolts to spec, and in the correct order?

What's the final outcome in regards to the gasket between the MEVI and the EGR tube?

 

Yes and have replaced it, I've taken the manifold off three times already, unless it's over tightened. I'm gonna try and disassemble and reassemble tomorow

 

Sounds like you're unaware of the torque sequence, and the exact torque specs, since you're unsure if it's over tightened or not. Details matter.

 

Not by memory I have it in my haynes manual...but the thing is with the throttle cleaner it isn't drawing in anything from or am I hearing any change in idle

 

just seafoam the car youll see the smoke if you have a vacc. leak

 

Seafoam it where....spray the whole engine or spray the inside or something

 

I've never had my MEVI activate properly.

My issue was with the vac can not keeping vacuum when i boosted. Has anyone come accross a one-way vac can. Eg - stores vac but not boost etc.

 

Sounds like your vac can doesn't have a check valve. Can be had for $2.50 at your local parts store.

 

PROBLEM SOLVED!!!!!!! Went and disconnected everything today to try and reinstall one more time... Everything looked good and I was about to give up when I looked at my MEVI. The bottom of it has a huge crack. So there is where I was losing all of my vacuum. It sucks I have to get another MEVI and this one is pretty much ruined, but atleast my car is running fine now with the USIM on. Thanks to everyone who pitched in and helped out, I learned alot and have pretty much have all new gaskets.

 

Good to hear. I knew you'd figure it out. Let the search begin for another MEVI!

 

If your still looking for the Mevi Kit Genuine Nissan Parts.com has it for $399.