240sx dies instantly pressing the brakes

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Oh my bad
Posts: 7
Joined: Fri Jul 14, 2017 2:58 am
Car: 1995 240sx RB25DET

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]Hey, So I have a 1995 RB25DET S2 240sx I've acquired. I've had KA's (which are super simple to work on), but this is my first RB. So far I've been getting everything up and running without issue. The car currently has no hood (waiting to get it back from paint) so the farthest I can drive it is around the block a few times because my local law enforcement gets pretty bored. That and the fact the police station is right down the road, lol.

So the issue I've run across is that the car runs and the motor is definitely strong. I have no issues at all with idle, no issues revving while parked. If I go for a drive and stay out of boost, the car runs perfect and stops with no issue. If I get into boost, there's no issue. Plenty of power. Then I press the clutch, still no issue. Then the brakes and instantly the car dies. There's no shuddering, no shaking, It just dies. But I turn the key (clutch in foot off the brakes) and it fires right back up like nothing happened. I'm running stock boost on the car on a stock tune until I know for sure everything functions as it should before modifying.

I found a few posts about a similar issue, but all of their cars bogged down and shuddered first. Could I be looking at a very large vacuum leak, or would that more lead to electrical cutting the power somewhere?

Sorry for the long post, I wanted to try to cover all the basics of the car.


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centralcoaster33
Posts: 2769
Joined: Tue Apr 05, 2005 10:41 am
Car: 240SX #5-1997
Location: Central Coast, CA

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I think you really just need to check the large vacuum hose that goes to your brake booster. Check it on all sides, the full length of the hose from booster to intake. There's a good chance it's got a break/ rupture in there, especially if it rubs or touches the sharp edges on the firewall. Please let us know how it goes either way. If it's not the hose, we'll come up with more ideas.

Welcome to NICO Club!

Oh my bad
Posts: 7
Joined: Fri Jul 14, 2017 2:58 am
Car: 1995 240sx RB25DET

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You know, I was thinking that same hose. I tried listening for the typical hiss of a leak but I couldn't hear one. I'll most likely be replacing it anyways after work today just to be sure. I drove it to AutoZone to grab a few things and it did it cut off on me once on the way there, but not on the way back.

The only things left to fix after that are the driver window rails and the windshield. And trying to get the darn thing to stay at operating temp. I see everyone having overheating issues, but I can't seem to get her to frickin heat up! Haha.

Thank you!

Oh my bad
Posts: 7
Joined: Fri Jul 14, 2017 2:58 am
Car: 1995 240sx RB25DET

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Well, I replaced the full vacuum hose off the booster but still no luck. It doesn't do it all the time, but it seems as if the harder you press the pedal the more it will. I also noticed the brake light flashes briefly when I stop.

I'm going to have a friend come over and try to bleed the lines. That would be my next idea. Maybe there's air in the line somewhere. Any other suggestions?

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centralcoaster33
Posts: 2769
Joined: Tue Apr 05, 2005 10:41 am
Car: 240SX #5-1997
Location: Central Coast, CA

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I think air in the brake lines would simply make for poor braking, not an engine idle problem. So, separate issue there (but brakes are important, so bleed them anyway). I wonder if something is wired incorrectly. Even so, I'm not sure what would cause the engine to just die with brakes applied. I thought the brake light would flash when brake fluid or even clutch fluid levels were low, but now I'm not sure. The engine swap has me thinking about it. I never know how the engine was swapped and what was modified to make the swap work. Does it use an OEM computer and can you check that for error codes? Voltage for the TPS could be wrong, so you could check that. Especially if it's one of the TPS with two plug sets (both three prong plugs, one with three wires, the other with only two).

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centralcoaster33
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Joined: Tue Apr 05, 2005 10:41 am
Car: 240SX #5-1997
Location: Central Coast, CA

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PS - might as well change your photo in the signature, since it's just the update your account logo because photobucket wants money to host nowadays.

Oh my bad
Posts: 7
Joined: Fri Jul 14, 2017 2:58 am
Car: 1995 240sx RB25DET

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I'm glad I bled the brakes. I did find a small amount of air. I checked, double checked and triple checked ALL vacuum lines, making sure each one was tight and found a hairline crack in the hose from the intake to the boost controller. I replaced that hose. I also ran a test on the electrical system to rule out the battery/alternator just for piece of mind. I can check the TPS tomorrow. It started raining on me today. It is running an oem RB computer, so I can check that tomorrow as well. I even cleaned the maf and did the screwdriver to the ear test on the injectors (yes, I know that method sucks but it was the best I could do at the time. Lol).

After doing all of that I went for a 30 minute drive and it didn't shut off on me. I'm hoping in all of that, I found the culprit, but I'm not calling it a win yet until I finish checking everything.

I do thank you for the ideas you're throwing and I'm trying to test them all!

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centralcoaster33
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Joined: Tue Apr 05, 2005 10:41 am
Car: 240SX #5-1997
Location: Central Coast, CA

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Awesome! Vacuum to boost might have been it. 'Cause the brake vacuum would eat up a lot of the other vacuum and maybe not leave enough for the leaking boost controller line? Keep up the good work and test driving.

Oh my bad
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Joined: Fri Jul 14, 2017 2:58 am
Car: 1995 240sx RB25DET

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Just when I thought it was fixed, the gremlin strikes again! Gah. So I'm going to go back over the vacuum lines once more. I did test for trouble codes. That was a no-go for any clues. Once it's finished raining during the day (damn you Florida) I'll run through and check voltages on the battery/tps to try to rule out a power drain.

I did try to recreate it with and without my fans on, and it happened in both situations. I really do need to run through the wiring on the entire harness, since my turn signals and wipers also do not work, even though it looks as if they are wired.. I'm just trying to subconsciously avoid anything to do with wiring and rule EVERYTHING else out before I have no other choice (lol). It is running a Wiring Specialties upper and lower harness (S14 to RB25det).

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centralcoaster33
Posts: 2769
Joined: Tue Apr 05, 2005 10:41 am
Car: 240SX #5-1997
Location: Central Coast, CA

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I like that Florida rain. Warm, wet and falls in big drops. Of course if I lived there, the frequency might bother me a bit. I can totally relate to not wanting to do wiring unless absolutely necessary. Have you been trying to spray carb cleaner around the intake and vacuum lines? That's a pretty good trick.

Oh my bad
Posts: 7
Joined: Fri Jul 14, 2017 2:58 am
Car: 1995 240sx RB25DET

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The rain is nice, but not when I'm trying to racecar, lol. I ran through the vacuum lines once more. Also using the carb cleaner spraying every line, and nothing. So it looks like I have some digging and testing to do.

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centralcoaster33
Posts: 2769
Joined: Tue Apr 05, 2005 10:41 am
Car: 240SX #5-1997
Location: Central Coast, CA

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I might be doing the same soon. Carb cleaner I mean. My idle get's all revvy sometimes. Bouncing a little at first, then bigger and bigger. Hasn't died on me yet, but gets close. I'm gonna check for vacuum leaks, check TPS voltage and look into possibly replacing my O2 sensors. Hopefully I can make time for that this week.

Oh my bad
Posts: 7
Joined: Fri Jul 14, 2017 2:58 am
Car: 1995 240sx RB25DET

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So, I realize it's been a while since I've replied. I've been so busy and frustrated. I think I finally solved the issue after replacing more vacuum hoses.

So, then, thinking all was well, I took the car to get the alignment and straighten the steering rack (my wheel was upside-down and annoying me). Now, I knew the car would be there a while, as there were others in front of me. So I got a ride back to the house, got some food and whatnot. And upon returning to the shop, I see my car running in the parking lot with coolant and smoke pouring out of it, four people (two being employees) just staring at it yelling that the car is smoking. Well, the burning coolant flowing out fried wiring, melted my fan relay, I lost almost all of my coolant in the time the car was running. On top of that, They sent me to a shop 20 miles away to get the relays they fried, and left me there until 11 PM repairing my car. My oil now smells like gasoline. My coolant is brown when it should be blue.

So, I've filed a damage claim with the offer of: if they pay for me to take the car to a performance shop (which I know a few of the guys at), go through the motor replacing broken parts, then there will be no lawsuit. Otherwise thwy can expect a large claim against them.

Sigh. And just when it was finally ready, too.

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centralcoaster33
Posts: 2769
Joined: Tue Apr 05, 2005 10:41 am
Car: 240SX #5-1997
Location: Central Coast, CA

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Holy Cow! That sucks. I got back to this thread because I found my issue yesterday.

I had both of my (there's only two) bolts for the EGR valve come off of my intake. They'd been working their way out for a while, with the idle getting worse and worse. Yesterday, the car died at the stop sign, then the stop light, then coasting to the next stop sign, etc. I fiddle for quite a while in some persons driveway. What sucked most was that I was racing to the edge of the fog so I could see the solar eclipse. The fog was too big for me and I didn't make it to the edge. So I missed the eclipse and had broken engine repairs for a couple hours. Well both bolts had slid out, one was gone, the other, just hanging in there. That was a huge vacuum leak, letting air in where the EGR valve gasket would go. I stumbled upon it, was trying to see if the valve could be lifted up by finger when I found the whole thing was loose on the intake. Not much room for a hand, but I had a tiny socket in the car and put the one bolt back on to hold it in place. That reduced the leak enough to run and idle again, so I took it to OSH and let it cool off. I pulled the bolt out again, bought a matching one and some washers, then installed it in the parking lot. Now, the EGR valve is connected as it should be, working, and the intake leak is gone, so my idle is stable again finally!

I missed the Eclipse and have to wait 7 years for the next one. I did fix my idle and EGR. Now, you shouldn't have to wait 7 years for your issues to get resolved, but man, that sounds bad. Overheating and melted parts/ wires... that is just terrible.

Get a lawyer friend quick. No messing around with your agreement/ threat. Make it all legit and plan for the worst case (battle in court) starting yesterday. Yes, plan to be screwed, hope for them to resolve it, don't let too much time go by while you hope they'll fix it. Timing will matter I think. The more chances you give them, hoping you'll be happy in the end, will likely result in them being less and less liable, to a point where you'll just be screwed and it's too late for justice. I mean, get a lawyer now I guess. I don't think it costs too much to retain one and have them help send and write the threatening letters/ agreements.


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