Car shakes violently and poor hp/acceleration

[romeoridgee]

93 300zx 2+2 non turbo

Alright here are the symptoms:

whole car shaking at idle
hp/acceleration is slow/dropped
when reving engine... its not normal, like heavy pounding in engine.
when trying to accelerate, each rumble the engine makes through the exhaust the car jerks.

Ive already changed all the spark plugs wasnt that.
unhooked maf sensor before starting it, no change.
I dont know what to check next and i dont want to go to a shop and have them tell me that i need a new motor.

has anyone out there had this problem before?

[t.mcginley.jr]

when reving engine... its not normal, like heavy pounding in engine.

This sounds like the engine is knocking, which could cause all of those symptoms. Can you take a video of it running? it will help us tell you what's going on.

You can also check for error codes:

http://www.nicoclub.com/archives/nissan ... ostic.html

[solaire]

I've got a 91 I'm trying to fix that's doing this same thing. I've replaced injectors, cleaned all the connectors, new plugs and it's still doing this. I have a code for the detonation sensor. Check for codes to see if you have the same code. I'm beginning to wonder if this is related.

[romeoridgee]

Alright I ran the codes, yes detonation sensor. It feels like it's running only half the engine.

http://m.youtube.com/watch?v=awpUhxtWk3s

http://m.youtube.com/watch?v=StvwzF_zB7g

YouTube videos of my car.

Plus my steering pump is messed up or something. When the engine is on and I turn the wheel there's some cranking noise coming from around the steering fluid reservoir.

I just hate how my car feels like it lost like 100 hp or so.. And the jerking.. That's not good..

Is this an easy fix?

[solaire]

It's hard to tell exactly by the videos but it seems you've got the same problem I do. Does it feel like if you try to give the car any gas it does the thumping and hesitates to go like it won't get out of it's own way? Also if you rev in neutral does it clear up past 3000 rpm?

If so, The 91 I'm working on has the same problem. I've replaced injectors and plugs so far in addition to cleaning all the problematic CAS and PTU connectors, coolant sensor connector and even swapped PTU, CAS, MAF and ECU from my running 90. (all needed since injectors were reading above 14 ohms) but I'm starting to think the detonation sensor is retarding timing. Is this a big repair? Definitely. The whole engine has to come apart to replace it but fortunately members of this site have found a way around it. The sensor can be mounted to the back of a cylinder head or to an intake plenum bolt. Google "300zx detonation sensor relocate" and read the info about it. Seems nobody has had issues on turbo engines but understand the reason behind why the sensor is where it is and what you're doing by relocating it. You can pick up a harness from Z1 (which is the source of the problem) for $20 and a new sensor (needed because you can't get to the old one) from ebay (look for one with OEM part #s) for around $35 free shipping which is cheaper than all the gaskets needed to remove both intakes and timing components to the original detonation sensor.

[romeoridgee]

YES!!!! EXACTLY!! Its like the engine doesnt want to get up on its own, so I have to shift at higher rpms.
I was looking online and z1 explains the whole problem with the detonation/knock sensor.

http://www.z1motorsports.com/product_in ... ts_id=1727

The reason why its sounds smooth at higher rpms, like z1 says, is because i cannot distinguish the noises coming from the engine.

So I myself, and others who have the same problem as me with the det/knock sensor, have 3 options. I read that this job could cost around couple thousand at a shop, f that. This would prob be either taking out motor, or plenum, and replacing the sensor itself and the wire (most likely the wire is at fault not the sensor itself). or by taking the transmission out and doing it from behind.
the second way, which is the cheapest, but not the safest, is to completely cancel out the sensor, tho incase there is knock, your ecu wont know it, and will continue to run normal with the knock, that would mess up the motor even more. and that fix is right here

http://www.z1motorsports.com/product_in ... ts_id=5580

Its just a plug and it gives back the same resistance as the sensor does under normal conditions... not safe at all..

and the 3rd and final one, the safe yet inexpensive one, is like what solaire said, to do the relocation. and this one guy explained it best, there are 3 different places to do it too. heres the link to it, he gives part numbers and everything.

http://www.twinturbo.net/nissan/300zx/f ... ation.html

So I will be doing this and hopefully it will fix the problem.
since they said that its most likely the wire going from the sensor to the sub harness, I will be getting this little guy here

http://www.z1motorsports.com/product_in ... ts_id=6565

and then i will get the knock sensor prob from CZP or even Z1, and then the bolts, and washers and nut from the hardware store down the street or where ever.

Hope these links help and will help those out there that has the same problem as me with the dreaded 34 code. I will post when its complete and give you guys the results of what happened.
Peace!

[solaire]

I just bought parts yesterday to fix this. You can get a sensor from eBay. You can find the Nissan part number 26xxx-0P300 or something like that for under 40 bucks. Z1 wants 80 plus shipping. Some relocation guides said eBay and I've seen threads here that say the same thing and they had no problems.

[romeoridgee]

yeah after i posted, i looked on ebay, and ordered one for 31 bucks, and then that triple covered harness for 30 including shipping, now to get the bolts.

but I always thought that my engine was in danger by driving like this. (not saying i am gunna drive it like this forever) but because its my daily driver im relieved that the car is trying to protect itself rather than make the engine catch on fire and killing me lol.

tell me after you do the relocation if it works.

[canadian booster]

great post with links too, for sure post back and see how it goes!

[romeoridgee]

thanks, and I sure will when i get all of the products and put them in.

[solaire]

Not only that detonation makes pistons melt. Not a good idea to let it run this way for too long lol

[romeoridgee]

what do you mean melting the pistons if i keep it this way for a bit?

[solaire]

If the computer can't stop detonation then you'll have very high combustion temps which will damage pistons maybe even valves. On the other hand when the car is in safety mode due to no sensor being seen by the computer it runs very rich since it advances (or retards?) ignition timing to prevent the engine from running strong enough to cause detonation and exess fuel without the correct spark timing can flood cylinder walls if left unchecked on top of fouling $100 worth of spark plugs.

My advice if you don't have to drive the car don't until the problem is fixed. I feel bad letting the 91 idle in my driveway much less driving the car around the block.

[Ziggy1621]

Also, have you done a balance test yet? Sounds like you have a pretty dead miss by what I can hear at the exhaust portion of your first video

[solaire]

Have you fixed it yet? Mine had the det sensor and cam sensor swapped on top of a broken wire at det sensor on the efi harness side plus I've got carbon problems on 2 cylinders

[romeoridgee]

Alright, last week I received the harness from z1, got the det sensor from ebay, and got the bolt and washers and nut from a hardware store. I had to take the actual bolt off of the plenum to compare the bolts.

I took off the negative part of the battery, unplugged the clip right behind the plenum, bolted the new sensor on the plenum, and then clipped in the sub harness.

After that I started it up, and ran rough for a bit, but after a few minutes it ran clean as a whistle. I turned off the car and put it in diagnostics mode and it said 55, clear codes. it worked.

Ive been running the car under protection mode for about 2 weeks. and after i fixed the codes, i took her for a run and now shes back to normal, she went fast lol. but it seems i went fast because i wasnt used to it. but it felt pretty good

Also, have you done a balance test yet? Sounds like you have a pretty dead miss by what I can hear at the exhaust portion of your first video

No I haven't done a balance test yet. I dont know what that is.

Have you fixed it yet? Mine had the det sensor and cam sensor swapped on top of a broken wire at det sensor on the efi harness side plus I've got carbon problems on 2 cylinders

I dont know about the carbon problems on two of your cylinders, before the det sensor fix i replaced all my spark plugs, next would be coil packs and injectors. no idea why there would be carbon problems...

Im glad that it wasnt a part of the wire between the subharness and the ecu.

[solaire]

Good to hear. This car i'm working on is for an older guy who doesnt drive it much. A carboned up engine is the Only thing I can think to explain higher compression on one cylinder and 0 on the adjacent cylinder. A piece probably broke loose with the leaking injector and lodged in the valve seat. It did seem to make a tick noise in the top end the morning I cranked it up and it ran bad. I'll be doing a leakdown test tomorrow to verify.

[romeoridgee]

all of that is out of my knowledge lol I dont know any of that. but good luck with that!! Did your z with the knock problem get fixed with the relocation?

[solaire]

nope the code was because of the broken wire on that efi portion of the harness near the connector but it didn't help fixing it. It at least made the car driveable but the 2 dead cylinders don't help much

[Ziggy1621]

A balance test is done by unplugging the coil packs one at a time. If the motor slows, then that cylinder is good. If nothing changes, then you've found a dead cylinder. Then try moving the coil pack to another cylinder to see if the miss moves with you. If not, ohm out your injector

[romeoridgee]

AAHHHHHHHHH Ive heard of that, just didnt know it was called a balance test, i thought you were talking about something with the exhaust. I will try that even though it seems like shes running on all six.

[solaire]

Exept in the case of this car i've replaced injectors and swapped in good coils. Compression on 3 was 0. Leakdown test revealed 81% leakage and the air was whistling out the throttle body so my problem is a bent or damaged intake valve and that's what's killing the other cylinders is the pressure from the combustion chamber being forced back into the intake during driving.

[Ziggy1621]

Ouch!

[solaire]

yeah i just was the unlucky one who happened to be driving the car when something broke. I think the engine is carbonned up. Guy hardly ever drives the car and never drives it hard. I bet he doesnt use 93 either. Only way to explain higher compression on #1. If not then that cam jumped a tooth and bent the valve. I'm waiting on a co worker's boroscope he ordered so i can look into the combustion chamber to know for sure.

[oriZnal]

romeoridgee, so ur problem got fixed with the knock sensor relocation? seems like mine's having same issue

[romeoridgee]

Yes. The relocation worked, though I would only recommend doing the relocation if your codes on your ecu read 34. Thats one step. But if its the wire that goes to the ecu, then your SOL.

BTW: I am not responsible for anything damaged due to performing this. Do this at your own risk. A little late for this. But DO YOUR RESEARCH. (Disclaimer)

Im glad that it wasnt the wire the subharness connected to. otherwise i would of been screwed.

[Luis macias]

I have the same problem with my z.. how can I check if it's the wire that goes to the ecu?