sr20det SUPER LAG until 4k rpm, full boost. HELP!!!

[drftsx]

ok, so after the shop had fixed my engine, oil blackage to cams and rocker arms, it runs like crap.

The car is very laggy. You can hear the turbo spool up at about almost 3k rpm, but the car/engine doesnt do anything until it hits 4k rpm, and then full boost. I just had some ras installed so can this be a reason who its lagging soooooooo much? Also, i've been doing a lot of research and some people say it CAN be the knock sensor, but never updated if it was or was not.

PLEASE SOMEONE HELP ME OUT HERE!!! CAR SUCKS *** RIGHT NOW!!!ALL HELP APPRECIATED.

THANKS

[theother1wstolen]

going to change mine today because when i give it gas the timing drops to more than 40deg BDTC and i have no acelleration, ill let you know how it goes.

[drftsx]

That would be EXTREMELY helpful. I've tried changing actuator back to stock, buying new exhaust gaskets and checking all my vacums. Also drove 30 mins to sacramento for shop to double check timing and it was good.

PLEASE LET ME KNOW IF IT IS THE PROBLEM!!

THANKS

[the converted]

Have you checked the cam timing?

[drftsx]

I had the shop re do everything, so i beleive the cam timings were done.

[youngun21a]

knock sensor,then go from there or vac leak.

[theother1wstolen]

well i just fixed my knock sensor, still no low end power, but i did notice that i have a mysterious vac leak, so i agree with the previous post, check the KS then vac.

[drftsx]

So did you fix the vac yet? If so, did it work?

[theother1wstolen]

i havent had a chance yet, had class all day. the problem for me with finding is that all of my vacuum lines are brand new silicone lines, so i dont have a clue where the leak could possibly be.

[drftsx]

Do you have any ras??? I am thinking it probably CAN be it becuse they were used so i dunno. Also, you think it can be bc of your turbo? I have a t25 with no shaft play and no broken seals.

[the converted]

Unless the RAS are physically holding the valves open it's not going to have anything to do with it.

[IanS]

That sounds like a knock sensor safe mode to the T. Have you checked your ECU codes? I would guess that your knock sensor harness has corroded or failed.

[drftsx]

I havnt checked for codes yet. I'll try an check. Also, does anyone have hks step 1 264 cams on bc i have them, and they sound super quiet, which i belive should not be.

Also, would a fult knock sensor cause it to lag until 4k and everything ok? Would it also quiet the cams too or what?

[IanS]

I havnt checked for codes yet. I'll try an check. Also, does anyone have hks step 1 264 cams on bc i have them, and they sound super quiet, which i belive should not be.

Also, would a fult knock sensor cause it to lag until 4k and everything ok? Would it also quiet the cams too or what?

The Sr ECU uses the knock sensor to cut down on emissions by idealizing the A/F ratio very close to the knock threshold. Its parameters allow it to due so any time the engine is below 4000 RPM.

When the sensor or sensor harness fails, the ECU retards the ignition timing to a safe zone. This causes the car to be increadibly laggy below 4000 rpms.

6 times out of ten the sensor is fine, it is the knock sensor sub harness that goes bad.

If you are still using HLAs with the cams, they should be nearly as quite as stock.

[drftsx]

I plan on getting a air flow meter soon just to be on the safe side.

I have read/been reading your post about similair situation. Is there anywhere i can buy a brand new sub harnes for knock sensor? I want to get a new one just to ensure that i didnt get a dead one.

Also, how much is it for a wold ecu, so i can just turn it off too depending how much it is.

Thanks

[IanS]

You can get the harness straight from Nissan.

As for the ECU, I have no Idea, Ive never looked into any Wold products.

[drftsx]

the harnss is the same as a ka one right? Does it matter if its ka3 or kade?

Im going to check for codes and then if its a knowck sensor code, probably get the harness.

[drftsx]

Ok, so after inspecting the car, i found out the the shop kind of moved some of the stuff around and as for some of the wires.

First, i used to have the igniter chip in the engine bay, and now, it hs been relocated near the ecu on the inside. I think this could be why its causing it. Could have done something with knock sensor harness. I'll check and let everyone know.

[drftsx]

Do you have a picture of the knock sensor harness, the plug/connector that connects to the knock sensor itself?

I checked my car yesterday, barely touched the knock sensor and it came off, either was loose or not even plugged in. I then took off starter and plugged in the knock sensor harness and made a clip from paper clip in order to lock the harness to the sensor. I started it up afterwards and vac went to 14 which went up. Also, i did a quick rev and it seemed good, but when i test drove it, it was the same.

Now, i have the negative battery terminal unplugged (for the night) and try to reset the ecu.

One thing i am worried about and am asking for a picture of the plug on the harness that connects to the knock sensor is becuse i notice something with the harness. On the knock sensor, there are two metal pronges. The plug on the harness tho, there is only one metal piece inside the holes that connect into the pronges. (thats the best i can explain). I dont know if it should only have one metal piece in the whole in the harness or both metal in both holes.

If someone can confirm if its just one or two. I beleive it should two because obviously there are two pronges. If someone can confirm this or give me a picture so i can confirm this.

Also, happy thanksgiving everyone.

[IanS]

There are 2 wires on the harness side, but only one on the knock sensor side.

One wire is a signal wire that goes from the ECU to the KS. The other is an interference blocking ground wrap. It runs with the signal wire, but does not connect to anything at the knock sensor.

Check your ECU code, you will probably have code 34 which is KS failure.

[drftsx]

I would do a check, but my brother (who owned the motor before me) said that we have a j4 ecu, which without the light, wont be able to check for codes. I will probably replace knock sensor with a autozone or kragen knock senor to see if it works. If not, i'll just get a new ecu later.

[IanS]

Even the J4 ECUs have diagnostics.

Im not sure whether they are OBD I or II but either way there is a way to check codes.

If its OBD I there will be a screw to turn, instead of an LED on the ECU, the blinks will be displayed through the MIL. Most swap guides do not say how to hook up the MIL, so you may need to wire it in.

If it is OBD II you will need to wire in a consult port and hook up a generic OBD II scanner. IIRC there are only 3 or 4 wires needed for the consult port, and wiring it up is pretty simple. The scanners can be rented at any auto parts store for little to no cost.

In either case, being able to read codes is an integral part of troubleshooting any problem. I suggest you figure out how to do so, even if not to solve this problem.