nathanong87

ok, well a couple posts below me there is an "idle drop" thread and although my symptoms are silimiar i'd like to provide as much info in my own thread rather than to derail that one.

prestory. took the car on a 300 mile trip to ocean city. got roughly 27 mpg on a s14 sr20det. 93 octane. ebay fmic, hks bov, stock turbo, 3" exhaust all the way, etc etc. this was my first full tank used by the car. oh yea i also have a walbro 255...dunno if that makes any difference.

so then on my 2nd full tank i filled it using 91 octane drove about 170 miles on it and just tonight, when it's raining no less (dunno if this makes a difference), i notice my gas level dropping FAST. like regardless if my gas gauge is correct, i lost about a 1/4 tank in 30 miles.....

1. losing gas (poor mpg)
2. idle drop, my car stalls whenever i go into neutral
3. lots of "pops" from exhaust
4. my white rear bumper is now "painted" black
5. am i supposed to be able to physically take the car out of gear even with the gas pedal depressed all the way down?....for some reason i am to .... not easily, but on my previous car this wasn't even possible WOT.

any input is appreciated... and as of now, i do not have any gauges to give u AFR or anything that make be useful to this discussion :hammer:

-Nathan

SleepR 240sx

First off thanks for actually taking the time to describe your problem in detail, helps us out a lot.

There are two obvious things that all your symptoms point to.

#1. You have a bad MAF sensor. The MAF measures all the air that enters your motor. If the sensor itself is bad, dirty, or damaged it will be sending the ECU the wrong information, thereby reducing your MPG. The "pops" your hearing is your car backfiring because you are running too rich. If the MAF isn't sending the proper information to your ECU your air/fuel mix is going to be way off,in this case causing the backfires. Coincidentally, your bumper being black is due to the constant backfiring and excessive fuel your burning. You can go to AutoZone and pick up some MAF cleaner and see if that helps your problem. You can also try cleaning out the electrical connector on the MAF to the harness with some Electronics Cleaner, also available at AutoZone. There should be a little clip that goes around the plug connecting to your MAF. On mine, the clip was missing so I have the connector ziptied to the MAF so it doesn't come loose.

#2. You have a bad vaccuum leak. You need to get a boost gauge. (Should be your first priority with any turboed car.) SR's should run at about 20 vacuum when idling. If you are running less than that you have a vacuum leak. A vacuum leak would cause all of the same symptoms as the bad MAF. Check through all your hoses, intercooler piping, and intercooler itself. If you don't find any obvious leaks, take some soapy water and spray it over your lines/pipes. When you start the engine you should be able to see air bubbles coming up from any leaks you have.

Also, something less likely to have this much of an effect though still something to consider if neither of the above avenues fix your problem is your BOV. If you are running it unrecirculated then the MAF will not be reporting the correct amount of air to the ECU because it is losing some when your BOV goes off, thus causing you to run rich. Usually this doesn't cause much of an issue with most people and I highly doubt it is your problem as you should have had these problems all along were it the cause. Also check your BOV diaphram, if it is ripped or torn it could be the culprit.

Try cleaning out the MAF and checking all your vaccuum lines first. If it comes down to it and you still can't find an issue there you can try out a new MAF sensor.
Also, when you converty your KA harness to work with the SR the MAF plug wires have to be extended to reach across the bay, so if someone did a junk job on your harness there could be loose wires where the MAF plug was extended causing your problems. But I would go through trying everything else before you get a new MAF or try tracing back your harness. Check the obvious first.

As far as coming out of gear, if the clutch isn't in then no you shouldn't be able to take it out gear. Probably just the age of the transmission. As long as it doesn't pop out on it's own accord I wouldn't worry about messing with it. If it ever does anything worse it will be cheaper just to find another used one than having someone repair your old one. Regardless that issue isn't connected with your other symptoms.

Good luck finding it and if you need any more tips just ask. Like I said make sure you get a boost gauge, very important for the health of your motor.

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nathanong87

thanks SleepR 240sx for the quick and lengthy response. after searching zilvia, google, and nico a little closer i had a pretty* good idea of what the problems were, but i did want to confirm my issue(s)

poststory: i started the car this morning and again the same idle drop (expected as i haven't done anything since last night)

popped the hoood and started looking at hoses...not just vacuum, but any and all hoses....turns out there was a loose hose that when from FMIC piping (non hot side (not the turbo side)) that goes to the intake manifold. I didn't do the swap for the motor , and there was essentially a hose connected to a smaller hose, with no clamp or anything connecting the two. Pure friction was keeping them together. SO that had come undone.

turned the car off. reconnected the hose (ziptied them, TEMPORARY) and restarted the car. Idle was remedied and after warming the car up, i took it down the street. Drove the car to a stop, where the car did NOT stall upon neutral.

Boost gauge on the way. are their any other gauges you or anyone would recommend. It would appear that with a sr20det motor , oil pres, egt, afr, and boost would be important

once again, thanks for the response

ps. as far as #5 that i listed, i knew that wasn't really part of the issue, but it seemed odd that i was able to take the car into neutral under WOT.... i mean it doesn't change any way that i drive perse, but it's something that i just noticed. i didn't think it was like that on my 300 mile trip, but this has me puzzled. when the rain stops here i'll peak under the car and see what's up. Would a missing tranny bolt or loose tranny bolt equate to the getting in and out of gear like i'm describing?

Ceepo

Boost
Water Temp
Oilpressure
EGT(exhaust gas temp)
AFR(not so important IMHO, everyone i have seen with one the bounce all over the place and doesnt read accurately)

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SleepR 240sx

No problem. Glad I could help you out.

As far as the transmission it could be a very worn out transmission mount or your synchros. Try checking out your mount first, if it's in good condition and not missing any bolts than I really wouldn't bother messing with anything else unless it starts popping out on it's own. Just my opinion.

For the gauges as I said definitely boost and Oil pressure is another big one for SR's. I don't know if you know of it but the pickup on the SR is right in the middle of the pan and very close to the bottom of the pan. This means that if you hit the pan hard on something on the road and damage/dent it it can cause your pickup not to get enough oil. Get a oil pressure gauge and check it often. Also doesn't hurt to invest in a skid plate or at least check your pan for damage routinely if you are lowered.

Get a wideband AFR if you have the money. I've found my stock water temp gauge to be fairly accurate but if you want to investing in an aftermarket one isn't a bad idea. EGT is pretty useful as well. Those would be the ones I would get first. There's not much else you would need in a street car other than those.

Also I would suggest you go through your engine bay as thoroughly as you can and look for any more loose lines. I'd say if whoever did the swap left one undone, there's a good chance there are more that aren't in good shap either.

Glad you got your problem taken care of, and just ask if you need anything else.

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