Weak SR? (dyno chart)

[Jeff240sx]

Turbine and/or compression, as well as double check the ignition. There is a larger problem than just the breathing. If that was a Mustang dyno I wouldn't be so worried, but...
Generally MAFS problems are noticable, as in sputtering, bad idle, running rich, ect. You can test it be checking the continuity over the pins.
-Jeff

[nlzmo400r]

thats a lil better, but put the exhaust back on and check all the areforementioned possible troubles? or did u already do that?

[8_6_Fo_Life]

We only disconnected the exhaust at the downpipe for the dyno run. After seeing the small gain we buttoned it back up and he's been driving like that since.

He hasnt gotten a chance to test anything cause it has been storming here all day. Tomorrow I believe he will be changing plugs (gapping somewhere from .28-.32), checking the MAF, and checking the turbo or damage or shaftplay or anything unusual.

Thanks again to all those shooting out ideas. Zilvia.net seems alright in my book.

[mrmephistopheles]

Originally Posted by 8_6_Fo_Life

I think it was a KA Diesel.

lol

Now THAT's funny.

[Bradman123]

better then 240sxforum for me so far... these types of experiences scare me. especially after what seems to be a bad luck streak for my sr..im excited to see what comes out of this.

[Dweezil]

At 300k miles I'd also check the fuel pump an make sure your getting enough fuel to start with.

[8_6_Fo_Life]

Originally Posted by Bradman123

better then 240sxforum for me so far...

Other then SR20Forum.com this seems to be the best tech/Nissan forum I've found. I dont even own a 240, but I've alreay learned a great deal about my friends car with trying to get his right. I appreciate it all.

Originally Posted by Dweezil

At 300k miles I'd also check the fuel pump an make sure your getting enough fuel to start with.

The car has a brand new Walbro pump...190 or 255 or whatever is normally used, cant remember. The car has great fuel psi at idle and steadily increases under boost. At times I have almost thought the car had too much fuel psi, but the a/f reading is obviously showing different.

[duey]

just to let you know i never made it to the dyno yesterday to get those a/f readings for ya. It rained so bad up here i decided not to drive the car. I will most likely get back on the dyno sometime next week, PM me or email me your email address and i'll send you my chart when i get it done.

[8_6_Fo_Life]

pm sent...thanks

[240silvia]

Originally Posted by mrmephistopheles

your only performance 'mod' is a FMIC.
If you're still on stock intake and exhaust, those numbers aren't terribly atypical. Maybe a bit on the low side, but not too low. Do you have a boost gauge to insure you're boosting at stock level (.5 bar / 7psi)?

Hmm on second hand.. they are kinda low.. have you performed a compression or leakdown test on that motor?

ookkkkkk....... I was going to post those exact words.... but.... he beat me to it! Plus if you are still on stock exhaust... that is WWAAAYYYYY restrictive! Mine is 3 1/4 off the turbo!!!!! LOL, upgrade exhaust, you will get a nice gain. Good luck bro...

[8_6_Fo_Life]

Originally Posted by 240silvia

ookkkkkk....... I was going to post those exact words.... but.... he beat me to it! Plus if you are still on stock exhaust... that is WWAAAYYYYY restrictive! Mine is 3 1/4 off the turbo!!!!! LOL, upgrade exhaust, you will get a nice gain. Good luck bro...

Read the whole thread.

The exhaust issue was covered many times...thats not the problem.

[Mike22bSTi]

Thanks for the help guys, unfortunately I haven't been able to perform any of the check ups and ideas you've offered and I'm going out of town tomorrow, which means it will be 5 to 6 days before I can mess with the car.

Here's a list I've compiled so far to look at:
1) Do a more thorough boost leak check
2) Inspect/replace my ancient MAF
3) Check coilpacks and plugs (properly gapped)
4) Inspect Turbo (believe it or not but after 7 months of owning the car I've never peered beyond the exhaust shield
5) compression check
6) reset ECU

As soon as I get back I'll perform all this and anything else you guys can suggest and I'll be sure to keep you informed. While I'm gone I'll still have occasional access to the web, so I'll stay in touch. Even if I can't my boy 8_6_fo_life, will take care of business. Ha! he's posted more than I have.

Thanks again

[Mike22bSTi]

Ok i'm back and i've had enough time to get some things done/looked at. Here's what i haven't had a chance to do yet and will be doing in the near future.

1) i haven't done a more thorough boost leak check
2) Inspect Turbo, easy but just haven't done this
3)compression check, will hopefully do this tomorrow along with the above

Here is what i have done

1) Inspected my MAF - looks fine, not so sure it's the original one, because it's in good shape, i didn't test continuity in the pins, i'll do that if nothing else pans out
3) Checked coilpacks and plugs (properly gapped)- i actually replaced the plugs and gapped at .032, and the old ones looked good. The coil packs and connecters were clean
4) replaced ka fuel filter with a 300zx TT unit
6) reset ECU - and i did get a code!

It flashed long once and short once, then repeated itself, which i believe is code 11, meaning CAS circuit... so that's interesting.

however i have no idea where to go from now, suggestions/thoughts?

[8_6_Fo_Life]

I drove Mike22bSTi's car today. It has a strange hesitation at tip in, any gear, and at WOT it stops pulling at about 5,000 @ 7psi. It will phsyically rev beyond and well to redline, but there is no power being made beyond 5,000 or so.

Boost builds quickly and strongly...holds steady for the most part, but it feels like its down making power by about 5k or 5500. One thing I noticed when making a hard/WOT pull in 3rd gear is that up near 6,000+ RPMs it almost looked like it was backing off 1-2 psi. I dont know if that is just the gauge reading inaccurately under load, or if the motor is truly making such less power that it makes less boost as well. Now keep in mind that he is running a 3" downpipe into stock '89 240 exhaust. Is it possible that the restrictive nature of the stock exhaust is actually building back pressure and decreasing the amount of boost in high level rpms? When we dyno'd the car with an opendown pipe it still didnt make a drastic difference, so I never noted this as a major factor. I just jammed about 30 questions into one paragraph...sorry.

He said he checked and got a Cam Angle Sensor code (11). Well, I'm not use to these types of ignition systems so does that mean the CAS is adjusted wrong, or faulty all together? It would somewhat make sense because it feels like it is either pulling timing at 5,000 or not advancing appropriately. Either way, the power is not there. BTW, timing is set @ 15*.

Any help would be appreciated, I am 99% it has to be a timing issue of sorts but I just dont know enough about this motor to start experiemting without consulting some of you guys on here first.

Thanks in advance and please excuse my 6000 questions at once.

[silverside]

get a known good CAS and retry

[Id-]

when the car falls flat on its face like that; its ignition timing!!! its not being advanced; or its being retarded for some reason

i'd guess because it was running lean; but if its throwing a code for a CAS, then i'd bet some money thats your problem since it is related to ignition advance
us 2jz-GE motor guys dont have a CAS we have a distributor

[Dream240]

Originally Posted by 8_6_Fo_Life

He said he checked and got a Cam Angle Sensor code (11). Well, I'm not use to these types of ignition systems so does that mean the CAS is adjusted wrong, or faulty all together? It would somewhat make sense because it feels like it is either pulling timing at 5,000 or not advancing appropriately. Either way, the power is not there. BTW, timing is set @ 15*.

Heh, that's what I thought. An ECU code rolling around in there. 100 bucks that's the prob. As far as the exhaust, doesn't matter for this type of power loss. Just power freed. Bigger exhaust will net more power not get the car back to normal range.

Good luck, keep us posted!

[Mike22bSTi]

thanks guys, looks like this is the problem so lets hope it pans out. I need to find another local SR owner, see if I can switch it out to confirm our suspicions.

I think I'll have to call JGY customs here in Virginia and see what they think... also see if they have any... does anyone know where one can source a CAS? I understand it's only found in SR motors and there is no USDM equivalent.

[TokyoNights]

You can usually find a used cas on ebay..also gap your plugs to .028-.030

[DuffMan]

I would be willing to bet good money, if you dynoed it with the knock sensor unplugged, you would see normal power levels.

[Mike22bSTi]

How much would you be willing to bet? say, the price of a new CAS?

why are you so confident? Do you think mine is faulty?

[Id-]

i doubt its knock thats causing the ecu to pull timing; i think its a defective CAS period; you can hear bad knock on a SR20 with a stock turbo; itsnot like a atmosphere-vent external wastegate or something

[DuffMan]

Haha, if its the CAS I'll send you mine when I go standalone.

[Mike22bSTi]

It's a deal duffman. However, a resolution for this will be delayed a bit as class starts tomorrow! And that always gets in the way of everything.

[Mike22bSTi]

I checked the ECU today again after it had been cleared and didn't get the CAS code again, just got back 55. I drove it plenty between clearing and rechecking. So who knows how long that code had been sitting, could be left over from the install if the CAS was unplugged temporarily. So i'm not so sold on this now as the solution...

[Mike22bSTi]

Ok, here is an update. I finally got around to a compression check and it came out good... abnormaly good
1- 168
2- 167
3- 168
4- 170

So, that was a releif..... Also i was able to swap my MAF with a known working one, and it didn't make any noticable difference. So 2 expensive possiblilities have been eliminated... and i'm at a loss again. But I'm nearly convinced it's a timming issue, something aint right with my timming, i just don't know what it is.

Next up is an extensive boost leak check (although i really think one would be more noticeable), Recheck timming and teh TPS and swap my coilpacks with my dad's Maxima's (how convenient!)

I also want to rule out the knock sensor, as DuffMan has suggested, however i understand the motor won't rev past 4 or 5k with it unplugged, is this so, how else would i check it?

Have i missed anything?

[Mike22bSTi]

After checking every flipping thing possible i got a chance to swap the CAS with a known good one and it made no difference, the original CAS just had a warped rotor and was rubbing against the optical sensor which would throw a code every once and a while.... On to the good stuff...

The ECU running my car is a 63 (for an automatic car), and today i swapped with a 62, And bam! runs like a champ. I had a BAD studer problem with the motor below 2.5k rpms, which actually had become a bigger issue than my powerloss because of the horrible drivability it produced. Now it's totally gone, it idles like a rock and i believe it feels stronger, however i want to get it on the dyno to know for sure so i don't get too excited.

Thank you guys for all your help, hopefully by this weekend i'll have it dyno'd, and i'll be sure to post and let you know how it all went down.

Respect!