View Full Version : SR making noise, can't rev high

08-18-2002, 10:32 PM
I've used the search function. Found a few things, but they don't help. Oh yeah, it's a red top SR20DET.

Here's my problem. My motor is making this puttering noise at idle and louder when I rev to 2500-3000rpms. From the search, it seems to me like it was a MAFS problem. So, I changed my MAFS from a good working '89 SOHC, still doesn't help. I've tried starting it up and removing the MAFS, still the same. Tried it with both MAFS. Car idles pretty good. I'm starting to think it's something in the head. Tomorrow, I'll do a compression test.

This sucks! I just got my car running for a month with my new turbo. http://forums.freshalloy.com/ubbthreads/images/icons/frown.gif Thanks for any help!

08-18-2002, 11:46 PM
Do you have a vacuum/boost guage? Sounds like a blowoff valve gone bad or a vacuum leak. Have you checked these items? also check the hose connection at the top of the blowoff valve, it may be connected to the wrong source.

hope that helps ya,

08-18-2002, 11:59 PM
Yes, I have a boost gauge. It's at -10, when it was running good, it use to be at -15. I've checked for vacuum leaks, there aren't any. When I had vacuum leaks in the past, motor just ran rich, but not like it's running now. I have the apexi twin chamber bov. There's only one way to connect this bov. The two chambers are connector together. The line from the engine goes to the rear.

08-19-2002, 12:04 AM
Take the blowoff valve off and check to see if the valve is seated or try adjusting it for more pressure to the spring to try to close the valve. At -10psi sounds like a vacuum leak to me.


08-19-2002, 12:05 AM
i think it is probably your mafs wiring... if you're sure you have a good mafs, you should really trace the wires for continuity and correct positions. it may seem like a PIA, but much easier than buying more parts that dont fix it! good luck...

08-19-2002, 03:22 AM
Add checking for blown exhaust manifold gasket into the mix, things like these is very hard to differentiate and gets real loud at 2-3k rpm. Ones between the manifold and turbo is a very common blow out failure on the SR.

08-19-2002, 04:21 PM
I'll take off the bov to check it and double check for vacuum leak today. I'm also going to double check the MAFS wiring. Haven't messed with the MAFS wiring since the swap, which is over a year now. Could wires have came lose? What's PIA?

I know it can't be the turbo to manifold gasket. I just installed a brand new OEM one with my new turbo. Which is less then a month old. I've also replaced the exhaust manifold gasket. The only ones that I didn't replace are the metal ones.

08-19-2002, 06:36 PM
Pain In the A ss...

08-19-2002, 08:09 PM
O.K. Just like I thought. Compression numbers came out all good. 160, 155, 150, 160.

I did fine that my MAFS wiring came undone. Rewired it up. Still the same. Changed new spark plugs because the old ones were all black, still the same.

I said puttering noise, actually sounds more like poping. Sounds like metal hitting metal. Could it be a bent valve? Would the car still start and idle? http://forums.freshalloy.com/ubbthreads/images/icons/frown.gif

08-19-2002, 10:19 PM
my car did the same thing when the swap was done. wouldn't rev higher than 2400 rpm. looked at the fsm for awhile and found that it was indeed the mafs. does your car seem to be hitting a limiter or will it rev higher than 2500 rpm? the fsm specifically said that the car won't rev past 2400 rpm if their's a mafs problem. carluch240 knows this because he did my swap and was present when this all happened. turns out a wire wasn't connected well enough under all the electrical tape...
check it again...

08-20-2002, 12:35 AM
I'll check it again tomorrow. I can rev past 2400 rpms. If I rev it slow. But if I rev fast or just punch the gas, it pops.

When you say under all the electrical type, you mean into the main part of the harness? I just checked to where I cut the wires to extend it to the other side.

08-26-2002, 10:51 PM
I've taken almost all the electrical tape off of the main wiring harness, still don't see nothing wrong. Now I have NO idea what it could be?

With the new plugs I can rev to redline now, , if I rev really slowly. Otherwise, still making poping sound. Vacuum at times is unstable at -10.

Anymore ideas???

08-27-2002, 12:52 AM
i would clear the existing codes, fire up the motor, let it act up on you and check for trouble codes, before ripping apart the wires or attempting to fix or change anything.

a tester would have helped you check continuity of your wires without having to remove the tapes...

08-27-2002, 05:06 PM
How do I clear the codes? There's a knob on the ECU, which way to turn?

I know I saw the LED flash codes on here somewhere?

08-28-2002, 08:01 PM
NONE of the above! I found out what's wrong now. One of my lifter arms, forgot what's it called, poped out. Here's the link for the pictures. www.eframes.com/default.asp?guestalbum=32472.1402 (http://www.eframes.com/default.asp?guestalbum=32472.1402)

My head is chipped, now I need a new head.

08-28-2002, 08:07 PM
That would be a rocker arm there. Where is your head chipped?


08-28-2002, 09:20 PM
On the grove where the valves goes up and down. It's chipped there. I think the valve springs would hit on the chipped part, it's not smooth anymore. I was thinking I could smooth it out with a grinder? Get a new rocker arm and be back in business. That rocker arm has scratches on it. I think the cam lobe might also have scratches, but I'll have to double check.