Car Feels Like It's Retarding In Cold Weather

[shotter]

It's really wierd. At night when it's warmish the car runs fine. But in the morning when the air is cold it gets up to about 5psi and the boost keeps rising but the car feels like it is running retarded. It doesn't missfire or anything like that it just feel like it has lost a huge amoutn of power. But it only happens when you try and rev it a bit. Crusing is fine. Any idea's?

[Adriano]

Could be R&R, when the air is colder it is denser, therfore it hits higher load cells

[shotter]

Could it also mean my AFM is on it's way out? Is there any way to test to see if R&R is comming into play?

[Tomei_33]

my car had same problems - mechanic said these are the causes

fuel pump

spark plugs

injectors

fuel filter

one of them is dirty.. hope that helps!

i changed my injectors since i was upgrading anyway.. and it worked perfect

Edited October 29, 2008 by Tomei_32

[FloydWestwood]

sounds like r&r. still got stock ecu?

[shotter]

Yea stock ECU running a haltech intercepter.

I might have to do some reading on R&R.

But ran the car again tonight and didn't miss a beat.....

So its just the cold air thats causing problems

[shotter]

Well i took it for a drive last night and it played up again. at about 6psi it would feel like the car is retarding and then the boost would spike up.... but this also happens with the boost controller off too so i dont think that the problem. I stoped it and let it sit for about 30 minutes. Straight away it didn't miss a beat for the rest of the night....

[shotter]

Ok this is becoming anoying, it seams that if i leave the car sit overnight or through most of the day it will run shocking as it his about 5 psi. if i drive it and then let it sit for 10 minutes it will run perfect from then on untill it's left for a few hours again. Any idea's?

[Tomei_33]

read what i said

[SL33K]

whats R&R?

I have the same prob. my car feels funny when its cold. Its smooth but its like it doesnt feel quick.

But when its warm and the weather is sunny it feels really nice and sweet.

I thought it was just me. i just services my car recently. it was a major service.

[trel]

clean the afm first before anything, it costs nothing and takes about 20 mins. removing/refitting. trust me these cars a LOT of problems can be traced to a dirty/dodgy afm. good luck!

[shotter]

Yea i think it's the AFM, i have cleaned it, i have replaced the fuel filter, spark plugs. i plan to change the fuel pump and i have bought a Z32 AFM. So i hope i can get this sorted soon. The other thing it does when it plays up, if you rev it out and keep the revs there it will missfire.

[bumble_bee]

you cant put an z32 on a stock ecu..

sounds lik R&R to me..ive got the same problem..wen could or hot...

i got a afc neo(untuned)..to try lean out my fuel abit..

so i drop the fuel from about 4000-6000rpm..wen R&Rs kick in..

and dependin on wat boost ur running too..

this was mention by SydneyKid

"It has been my experience that RB25's run a little lean down low in the rpm range (Nissan do this for fuel economy and emissions) and a lot rich up high (Nissan do this to protect the engine). So I have to increase the voltage (using the SAFC) up to around 3,000 rpm and decrease the voltage over 5,000 rpm.

The real problem is in the 3,000 to 5,000 rpm range as the engine comes on boost. They really need lots of fuel very quickly in this area. This can mean that you need to increase the voltage (that the ecu sees) over 5.1 volts to get the right A/F ratios. The ecu then goes into engine protection mode, rich and retarded (sounds like a girl I knew once). Past that rpm you can start leaning it out as it runs too rich, so the voltage needs to be turned down under 5.1 volts. The ecu sees this as the engine not needing protection mode any more, no more rich and retarded.

So you get good performance up to 3,000 rpm, then sluggish from 3,000 rpm to 5,000 rpm and then good performance from 5,000 rpm and over. The SAFC may not help this, in fact as explained above, it can in fact make it worse if the tuner is not switched on to this stuff.

With bent afm voltages, the ecu (tricked by the SAFC) also fires the ignition to suite the airflow it THINKS the engine is getting. This is not a good thing as you generally end up with ignition that is too far advanced in some rpm ranges.

The poor tuner has to juggle the SAFC settings, so that the A/F ratios are OK, the ecu doesn't get into rich and retard (engine protection) mode and the ignition timing is not too far advanced so as to cause detonation. My experience (I am not a good tuner) has been that this is full of compromises, sometimes you just can't win and have to reduce the boost level a bit to get even a reasonable compromise.

Keep in mind that this explanation is very simplified to make it fit in a reasonable space, the rpm's used are rough guides only and every car is different. "

but ur answer is aftermarket ecu...

but wat mods u got?

but check the obvious lik plug gapping..clean ur afm with some good electrical cleaner...coil-packs?

hope this helps...

[SL33K]

any tutorial how to clean AFM ?

Edited November 7, 2008 by VishR33

[some_cs_student]

Pretty sure there is something in either the tutorials section, OR there should be one when searched, I've seen them around before.

[shotter]

I found today that drove it untill the car warmed up. Only a few minutes. and it was playing up as usuall. Then turned the car off for 15 seconds. Started it up and the problem was gone...... Still confused.

[TUF250]

did you ever solve this?