S13: rough idle, no power - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

S13_conv · 10-14-2018, 09:51 PM

I need help please. Original owner bone stock 94 S13 DOHC convertible. 160K mi. No oil leaks. It’s OBD I.

It started running very rough, a rough violent shaky idle and no power on acceleration. No CELs. It is time for a tuneup so I replaced cap, rotor, plugs, plug wires, fuel filter, and a few vacuum hoses. Topped it off with good fuel. Same condition however. Remote ign coil and ign control module seem ok. Both getting power and ground and secondary resistance is 16K ohms. Sprayed carb cleaner at many places and don’t find any broken vacuum points. Throttle body is clean. Air filter clean. Getting strong spark from all four plugs wires.

I did a compression and cylinder leakdown tests. Hot compression is a bit low: 170-165-170-165 but still fair and leak down results show ok at 20% loss in all cylinders at 100psi so the head and the bottom end of the motor are sound.

Head gasket is not leaking since oil is clear and the leak down test would have discovered a cracked water jacket. So it’s not this.

Disconnecting the maf connector while idling does nothing to change the behavior.

Crank and cam position sensors must be ok since it starts and runs. And since I have spark, the ign coil and ign control module must be sound, right? How would I test the distributor? What am I missing?

Yes, I’m new here.

Jfornachon · 10-15-2018, 11:48 PM

Is there a code when you disconnect the MAF. If not then you have found your issue.

EFITTZY · 10-16-2018, 06:52 AM

Sounds like a bad MAF...
Having similar issues with my 93 vert, however when I disconnect the maf plug the car dies.
I'd start looking around for a known good maf and go from there

S13_conv · 10-16-2018, 09:20 AM

Thank you, both of you. I will find a maf. Indeed in my case it’s not setting a cel when unplugging it with it running. The motor runs so badly with or without it connected; it feels like it’s running on one or two cylinders. I havent experienced this kind of terrible behavior from just a maf before but diagnostics are a lot more logical with obd II. I’ll report back later.

S13_conv · 10-16-2018, 06:55 PM

Folks, I lied. Disconnecting the MAF while idling kills the motor and sets the CEL as it should. Working on a few cars and I forgot which was which.

I found the problem though with this thing. The EGR valve won’t inflate (hold vacuum), nothing. That’s the cause of the massive stumbling and power loss. It’s diaphram is toast. Strangely, a new EGR valve can’t be had locally or online, not even my local Nissan dealer lists it. What gives? EBay used varieties do not look like mine so getting a good used one is a non starter. Can you fine folks point me to useful instructions to bypass this valve and a parts list/links including the size of the cap I’ll need to buy to cap the tube to the exh man please? Assume I can simply plug the vacuum hoses to it. Thanks in advance.

EFITTZY · 10-17-2018, 01:57 PM

There are detailed videos on YouTube if you are a visual person like myself.

You can also use the search function to find several write up's on this forum and others that will be useful.
http://tech.240sxone.com/115/ka24de-egr-removal/

They do make egr delete plates to entirely block off the valve. Here is an example:

https://frsport.com/circuit-sports-e...SABEgIiTfD_BwE

Best of luck, very cool that you are the original owner

S13_conv · 10-17-2018, 05:05 PM

I’m guessing that’s the only option is a delete. Appreciate the links very much. I had a 90 300Z twin turbo I bought new as well. Sold it due to too many wheels at the time. Convertible was a keeper but in reality I wish I had done the opposite.

Jfornachon · 10-17-2018, 08:23 PM

If you want to diag the egr take pop can and cut a bunch and make your own that goes between the valve and manifold. This will block off flow and maybe confirm it. If it doesn't work then the block off wont help either. YOu will also want to plug off the vacuum line going to the valve so that you don't have a vacuum leak from the damaged diaphragm in the valve.

Have a great day,
jared

S13_conv · 10-18-2018, 07:33 AM

Thanks Jared for your tip, but the diaphram in the egr is torn. It’s confirmed by reaching underneath to see there’s no resistance when pushing up on it. Plus it won’t hold any vacuum. I’m looking into bypass options.

Jfornachon · 10-20-2018, 10:11 PM

I gathered that it was. I was just suggesting something to try before spending money on something that you don't need. If you use the block off method I suggested you will save ome money that can go towards other things. That is unless you have a lot of expendable money just sitting around.

Have a great day,
jared

S13_conv · 10-29-2018, 03:25 PM

Well I received the EGR block off plate and bolts from the link the individual pointed me to above. For the M24x1.5 plug, I had to source it from eBay since even my local two commercial fastener guys do not carry that. I’ll tear into the work this weekend.

10-14-2018, 09:51 PM	#1
S13_conv Join Date: Oct 2018 Location: WA Age: 62 Posts: 6 Trader Rating: (0) Feedback Score: 0 reviews	S13: rough idle, no power I need help please. Original owner bone stock 94 S13 DOHC convertible. 160K mi. No oil leaks. It’s OBD I. It started running very rough, a rough violent shaky idle and no power on acceleration. No CELs. It is time for a tuneup so I replaced cap, rotor, plugs, plug wires, fuel filter, and a few vacuum hoses. Topped it off with good fuel. Same condition however. Remote ign coil and ign control module seem ok. Both getting power and ground and secondary resistance is 16K ohms. Sprayed carb cleaner at many places and don’t find any broken vacuum points. Throttle body is clean. Air filter clean. Getting strong spark from all four plugs wires. I did a compression and cylinder leakdown tests. Hot compression is a bit low: 170-165-170-165 but still fair and leak down results show ok at 20% loss in all cylinders at 100psi so the head and the bottom end of the motor are sound. Head gasket is not leaking since oil is clear and the leak down test would have discovered a cracked water jacket. So it’s not this. Disconnecting the maf connector while idling does nothing to change the behavior. Crank and cam position sensors must be ok since it starts and runs. And since I have spark, the ign coil and ign control module must be sound, right? How would I test the distributor? What am I missing? Yes, I’m new here.

10-16-2018, 06:52 AM	#3
EFITTZY Zilvia Junkie Join Date: Mar 2016 Location: I n d i a n a Age: 25 Posts: 323 Trader Rating: (0) Feedback Score: 0 reviews	Sounds like a bad MAF... Having similar issues with my 93 vert, however when I disconnect the maf plug the car dies. I'd start looking around for a known good maf and go from there __________________ (づ｡◕‿‿◕｡)づ T E A M B L O O M

10-17-2018, 01:57 PM	#6
EFITTZY Zilvia Junkie Join Date: Mar 2016 Location: I n d i a n a Age: 25 Posts: 323 Trader Rating: (0) Feedback Score: 0 reviews	There are detailed videos on YouTube if you are a visual person like myself. You can also use the search function to find several write up's on this forum and others that will be useful. http://tech.240sxone.com/115/ka24de-egr-removal/ They do make egr delete plates to entirely block off the valve. Here is an example: https://frsport.com/circuit-sports-e...SABEgIiTfD_BwE Best of luck, very cool that you are the original owner __________________ (づ｡◕‿‿◕｡)づ T E A M B L O O M

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

10-15-2018, 11:48 PM	#2
Jfornachon Zilvia Junkie Join Date: Dec 2011 Location: Caldwell Idaho Posts: 300 Trader Rating: (3) Feedback Score: 3 reviews	Is there a code when you disconnect the MAF. If not then you have found your issue.

10-16-2018, 09:20 AM	#4
S13_conv Join Date: Oct 2018 Location: WA Age: 62 Posts: 6 Trader Rating: (0) Feedback Score: 0 reviews	Thank you, both of you. I will find a maf. Indeed in my case it’s not setting a cel when unplugging it with it running. The motor runs so badly with or without it connected; it feels like it’s running on one or two cylinders. I havent experienced this kind of terrible behavior from just a maf before but diagnostics are a lot more logical with obd II. I’ll report back later.

10-16-2018, 06:55 PM	#5
S13_conv Join Date: Oct 2018 Location: WA Age: 62 Posts: 6 Trader Rating: (0) Feedback Score: 0 reviews	Folks, I lied. Disconnecting the MAF while idling kills the motor and sets the CEL as it should. Working on a few cars and I forgot which was which. I found the problem though with this thing. The EGR valve won’t inflate (hold vacuum), nothing. That’s the cause of the massive stumbling and power loss. It’s diaphram is toast. Strangely, a new EGR valve can’t be had locally or online, not even my local Nissan dealer lists it. What gives? EBay used varieties do not look like mine so getting a good used one is a non starter. Can you fine folks point me to useful instructions to bypass this valve and a parts list/links including the size of the cap I’ll need to buy to cap the tube to the exh man please? Assume I can simply plug the vacuum hoses to it. Thanks in advance.

10-17-2018, 05:05 PM	#7
S13_conv Join Date: Oct 2018 Location: WA Age: 62 Posts: 6 Trader Rating: (0) Feedback Score: 0 reviews	I’m guessing that’s the only option is a delete. Appreciate the links very much. I had a 90 300Z twin turbo I bought new as well. Sold it due to too many wheels at the time. Convertible was a keeper but in reality I wish I had done the opposite.

10-17-2018, 08:23 PM	#8
Jfornachon Zilvia Junkie Join Date: Dec 2011 Location: Caldwell Idaho Posts: 300 Trader Rating: (3) Feedback Score: 3 reviews	If you want to diag the egr take pop can and cut a bunch and make your own that goes between the valve and manifold. This will block off flow and maybe confirm it. If it doesn't work then the block off wont help either. YOu will also want to plug off the vacuum line going to the valve so that you don't have a vacuum leak from the damaged diaphragm in the valve. Have a great day, jared

10-18-2018, 07:33 AM	#9
S13_conv Join Date: Oct 2018 Location: WA Age: 62 Posts: 6 Trader Rating: (0) Feedback Score: 0 reviews	Thanks Jared for your tip, but the diaphram in the egr is torn. It’s confirmed by reaching underneath to see there’s no resistance when pushing up on it. Plus it won’t hold any vacuum. I’m looking into bypass options.

10-20-2018, 10:11 PM	#10
Jfornachon Zilvia Junkie Join Date: Dec 2011 Location: Caldwell Idaho Posts: 300 Trader Rating: (3) Feedback Score: 3 reviews	I gathered that it was. I was just suggesting something to try before spending money on something that you don't need. If you use the block off method I suggested you will save ome money that can go towards other things. That is unless you have a lot of expendable money just sitting around. Have a great day, jared

10-29-2018, 03:25 PM	#11
S13_conv Join Date: Oct 2018 Location: WA Age: 62 Posts: 6 Trader Rating: (0) Feedback Score: 0 reviews	Well I received the EGR block off plate and bolts from the link the individual pointed me to above. For the M24x1.5 plug, I had to source it from eBay since even my local two commercial fastener guys do not carry that. I’ll tear into the work this weekend.