Jump to content
SAU Community

My R33 is in "limp home mode", why/how to fix! :(

chicane

By chicane,
in R Series (R30, R31, R32, R33, R34)

 Share

Recommended Posts

chicane Community Regular

chicane

Posted
Posted

Hi All,

I am having problems with my R33 GTS4 with the ECU seeming to be in limp home mode (I can't rev it over 2500 RPM).. ive tried the following things:

- Reset ECU (Battery Disconnect)

- Pulled out ECU, diags return 5-5 (All OK)

- Changed Oil/Fuel Filter day before (all fine after changing these, drove about 25km on Sat night and 25km on Sunday morning)

- Problem exists still with Disconnected AFM

- Thoroughly cleaned AFM element/plug with electrical contact cleaner

- Just disconnected battery to ensure the ECU completely resets (will be left for about 6 hours)

Any tips/advice is appreciated.. driving under 2.5K rpm sucks!! and I'm worried it may be bad to drive in limp home mode for long..

chicane

chicane Community Regular

chicane

Posted
  • Author
Posted

Hi all,

Thanks for the replies.

The ECU is stock.. the car is basically stock except aftermarket exhaust / K&N pod filter.

Is the AFM for N/A skyline the same as turbo? Could I try an AFM off a turbo skyline?

Regards,

chicane

Cecam Enthusiast

Cecam

Posted
Posted

Most AFM faults are just dry joints which are easy to repair if your handy with a soldering iron... swap it with a known good one and if that fixes it, just open up your one and it will likely be one of the pins that goes off to the socket will be bad...

chicane Community Regular

chicane

Posted
  • Author
Posted

Hi All,

An update to the ongoing saga... after leaving the battery disconnected for ~6 hours yesterday (and after cleaning the AFM with electrical contact cleaner) I go back to the car and start it up, and revs past 2500 no worries. What im trying to work out is if my car was indeed in limp home mode, or it wouldn't go past 2500 rpm because thats when it switches from the O2 sensor to the AFM?

Manage to get home (~15km) in peak hour with no problems at all. This morning, I start it up, and after letting her warm up I'm sure its all good. Drive about 750m up the street to the main road, Stop at the stop sign, turn and then i cant rev past 2500 again :| I pull over, pop hood, disconnect afm plug when the car is running, car stops. So I plug it back in, start her up, and she can rev past 2500 again, drive all the way to work (~15km) with no problem at all.

What gives? I was thinking the problem may have been caused initially by the oil type K&N filter, and as my car was in the sun all day maybe some moisture got sucked over the AFM element or something.. I dunno..

One thing that is similar from this morning and Sunday night, was I could drive for about 1km, then after stopping, the problem arises..

Comments appreciated! :P

cheers

chicane

PranK Grand Master

PranK

Posted
Posted

some sort of AFM plug prob or something, so what they said up ^ there, borrow a good one, test it - if its all good then pull yours apart and try to resolder everything or just buy a new one i guess...

I once accidently changed the type of AFM in my power fc to Z32 AFM and the thing was the same... wouldn't rev past 2500 and was coughing a lot...

chicane Community Regular

chicane

Posted
  • Author
Posted

Hi all,

Last night I headed down to a friends place to borrow an AFM from an R33 GTST (cheers AdamR33) , on the way down there the problem arose 3 times again.

- First, after travelling 5km from home on the freeway (100km/h) I stop at an intersection, turn, and the problem occurs - Cant rev over 2500rpm! I pull into a servo with car running, pop hood, unplug AFM, car stalls, plug AFM back in, start car, problem gone.

- I drive another 5 km, repeat process, then another 5 and repeat process.

Get to my mates, change the AFM over, and I've managed to drive 25km back home and to work today (10km'ish) with no problems.

Seems it was the AFM after all. Many thanks for replies helping me with this, now I need to find where to get a replacement/how to repair this one!

Is there any way I can measure levels on the pins to determine what the fault is?

Regards,

chicane

Cecam Enthusiast

Cecam

Posted
Posted

I wouldn't bother measuring the levels. Remove the thin plastic lid (it is simply siliconed in place, be careful not to cut through the lid that folds back under though) and then you'll see where the pins go from the plug in the case onto the PCB. Theres usually where the problems at, you might want a fairly grunty soldering iron as the tracks/pads/pins are all quite thick so need some decent heat to flow the solder properly. Theres bugger all on the pcb (which hides under copper sheild), you might as well resolder that for good measure. Throw the lid back on and should be fixed...

Have fun...

Alex Au Contributor

Alex Au

Posted
Posted

that's for sure turn into "fail safe mode" & 99% is the AFM. I dunno how & what u used to clean your AFM.

1. U hv to take out the AFM & spary the elect contact cleaner(don't use other stuff...I use 3M & its really good) directly to the hotwire

2. leave the AFM stand straight & let the cleaner dry up

3. If u hv a wet type filter. Try use a towel dry it up a little so no more grease suck during engine run.

chicane Community Regular

chicane

Posted
  • Author
Posted

Hi thanks for the replies!

Since I had this problem I did initially try cleaning the hotwire in the AFM (the stuff I used was CRC electrical contact cleaner, same stuff really) I did what you mentioned.. and the problem still existed ;(

I borrowed a friends AFM (known good) and I have not had the problem once since I've used that (maybe 2wks now?) .. I have a K&N oil type pod, I dont think that has let any oil come through but I don't know..

I think I may have to just bite the bullet and buy a 2nd hand one.. I might pull it apart and have a look and see if anything is obvious (cracked solder tracks etc) but I think the hot wire could be at fault here..

Cheers

chicane

that's for sure turn into "fail safe mode" & 99% is the AFM. I dunno how & what u used to  clean your AFM.

1. U hv to take out the AFM & spary the elect contact cleaner(don't use other stuff...I use 3M & its really good) directly to the hotwire

2. leave the AFM stand straight & let the cleaner dry up

3. If u hv a wet type filter. Try use a towel dry it up a little so no more grease suck during engine run.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • iain_ST44GA
      M35 VQ25DET starter motor

      By iain_ST44GA · Posted

      Hi Guys, Does anyone know any aftermarket part numbers for a starter motor to suit the VQ25DET? I can find lots of alternative part number for the VQ35DE, which I assume would fit, but there is a lot of conflicting information out there. Thanks..
    • Murray_Calavera
      R33 GTR running -9 with no tune

      By Murray_Calavera · Posted

      I don't understand how this hasn't boiled down to - Upgrade the turbo when you have everything required. ECU, injectors, fuel pump, turbo, etc. Do it all at once.  If you don't have everything required, just enjoy the car as it is and keep saving up your pennies. 
    • Duncan
      R33 GTR running -9 with no tune

      By Duncan · Posted

      Sounds like you've got an interesting adventure ahead here with local support if you have trouble! My guess is that, unboosted, you will be OK with a small upgrade like -9. What will happen is that once the stock ECU sees more airflow than it expects it will add a heap of fuel and pull a heap of timing to be safe because it can't understand how it could get that much air without there being an issue. You will see clouds of black smoke and it won't pull hard through the midrange and top end. So, overall it will be a bit frustrating but should be OK. If you are still nervous set the base timing back 2o through the CAS, but it will be even more sluggish everywhere. As said above through...this is not my guarantee your engine won't be blown into a million pieces, leaving you looking for very hard to find parts A better idea is get a computer with logging ASAP, wire in a wide band O2 sensor and a use remote tuner. I've done multiple cars this way and while it is not as good as a specific tune on a dyno they can get it 90% right. I'd suggest if you can afford an R33 GTR these days you can afford an ECU and tune. And if you can't afford that you sure won't be able to afford the rebuild if it goes bad in the meantime,.  
    • Duncan
      New kid on the block

      By Duncan · Posted

      Yeah it would be nice if someone took the time to put that sort of information together, but there are a lot of variations in looms. I think you are making this way hard for yourself if you just want to get it running....sourcing an SR20 with the right wiring will be a billion times easier than matching the RB loom to an S15 chassis. If you do end up going this way, you just need to trace every wire in the loom with a multimeter, 95% of them will go to a location you can confirm at the ECU.....and then post it up for the next person who needs it  
    • Duncan
      Coolant leak?

      By Duncan · Posted

      Just top it up with water, and keep a general idea of how much you added. It is normal for water to be pushed into and pulled out of the reservoir through the cap, and it should not be more than half full or it will be likely to overflow when hot. Any decent mechanic can do a pressure test of the cooling system to confirm if you have a leak. Keep in mind if it is only leaking a little and when hot it may well evaporate before you see it hit the ground
×
×
  • Create New...