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ECMlink Lots of part-throttle knock on stock 91

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Kenneth Schlorf

Proven Member
90
9
Feb 15, 2015
Cottage Grove, Minnesota
1). Any boost, vac, or exhaust leaks?
No major leaks.

2). Verified mechanical timing?
Unknown - that's one reason I am writing this post.

3). Verified base timing?
12/8/2016

4). Ignition system
COP or Stock Coil: Stock
Wire brand and Age: NGK - 2 months old
Spark Plug brand, type and Gap: NGK BPR6ES - stock gap

5). Motor health (Compression Test)
Good - within 5%

6). Performed basic throttle body adjustments?
Idle Switch: yes - see log
Throttle Cable: yes
TPS: yes
BISS: yes - bottomed out - reason for this post.

7). Compression ratio
Stock

8). Any known bad sensors or brittle wiring?
No - this is with a new knock sensor - was doing it with the old one, too, which lost all its goo.

9). Any DTC/CEL codes?
No.

10). Electrical system
Car off (not running): good
Car running: good

11). Base fuel pressure and injector values
Base Fuel Pressure: Stock
Injector Size (cc/min): Stock - just cleaned and balanced

12). Properly calibrated and configured wideband sensor
Sensor Brand: NA - Stock
Calibration Date: NA - Stock

13). Type of fuel
Type: Unleaded 87 octane
Percent of Ethanol:

14). Watched ECMlink how-to videos?
Yes
_________

Mods to my my 1991 Eclipse GSX 5-speed:
  • EGR Block-off
  • Evap and hoses disabled/removed
  • K&N
  • Removed silencer
  • ECMLink V3
  • that's it!
I am wondering someone would be so kind to look at this short log. I have been having trouble with idle (surge) at what I believe is a relatively specific engine/coolant temperature. It's not bad (annoying) and I gave up trying to fix it for the winter. I put my 92's ECU with ECMLink in the 91 and am getting tons of knock. I thought my knock sensor was bad (all of its goo is out) so I replaced it and that didn't get rid of the knock. I am now suspecting the guy who did the timing belt (previous owner - I just picked this thing up in April) may have the timing off. Before I jump in and buy all new timing belt parts (because he didn't use Mitsu stuff), I am wondering if the timing being off could cause both the idle and the knock issue. Thoughts?

Thanks for reading!
Ken
 

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I appreciate your honesty and realize that few people may offer suggestions; however, I was hoping someone might be willing to say from their experience that the timing being off might cause the issues I am having so that I have an idea before purchasing parts and figuring which upcoming day might just have above freezing temperatures for me to work on it. It may not be hard to verify, but asking is much more simple. Again, I appreciate your honesty and suggestion.
 
Why are you using 87oct? Our cars need premium gas 91 or higher. Probably a good reason you see so much knock. Also like said above check the timing marks out, they either line up or they don't ;) if the timing was off you would either not run or run like crap and probably be bending valves! So if it was off by more than 1 tooth you would know. But really you need to check no one can tell you if it's it or not. 1g's have a real aggressive timing map and expect to have premium gas. Have you tried bringing the timing down around where it knocks? Also how much boost are you trying to run and what turbo?
 
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JP, I appreciate you jumping in to offer suggestions. In my '92 GSX the gas door and gauges say "Premium" fuel, but the '91 doesn't - either way, it shouldn't be knocking like in the log at 33% throttle with 87 octane, so that is not the problem. This car has never seen a boost controller and is completely stock relative to boost (the restrictor is still in the BCS nipple) and just about everything else.
 
My 91 says premium in the gas door ;). What is the knock cell set at? Can't look at your log at the moment. Like I have mine to see knock 3* and higher and to be active about 3000rpm and 30% tps. What's yours set at? If it's to low it could just be phantom knock.
 
I wonder what the diff is regarding the "Premium" label then...hmmm... you have a 1G Eclipse Turbo or are you referring to your GVR4? Anyway...

Knock CEL is set at 3* and it activates at 2200rpm and 0% throttle (not sure if those last two are factory settings, but I have never messed with them).
 
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Try moving the rpm to 3000 or 3300 and tps to 30%. That right there could be why your seeing knock so early. How many counts do you get? And i just checked it does only say unleaded on my gvr4 fuel door. But if you look in the owners manual it says to use premium fuel. Even with premium if I run more boost than stock I'll get some knock up top unless I lower the timing in that area. The map for 1g is super aggressive. Some guys switch to the 2g or evo maps when using pump so it won't knock as bad. Also when you set base timing did you use link to ground out the ecu, before checking? You could also try tightening up the spark plug gap abit and see if it helps.
 
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No one can just tell you your timing is off. Literally before you typed this whole post out you could have walked out, checked it, and came back inside. I know working in the cold sucks. Just bundle up :). Also there is no way you should ever put 87 in a DSM. If you cant afford the extra few dollars for premium you probably can not afford to own one. Again not to sound harsh, but 87 is not good for your car at all and as kauai stated, especially a 1g map.
 
This was supposed to be a simple post and a matter of the DSM community reading my post and merely suggesting (if someone felt so inclined): "yes...I have heard of timing being off causing lots of knock" or "no...timing being off a tooth wouldn't cause lots of knock." Because I don't know the answer to that, that's the type of answer I was looking to get in response.

Thanks for jumping in with your thoughts jakk220. Maybe I am over-thinking it: to check timing, don't I have to take the timing belt covers off (upper and lower)? Or are you suggesting to check the timing of the camshafts only (I am assuming I would at least want to check timing with the crankshaft, too.) That most certainly could not be done in the time it takes me to type this - hot or cold outside - unless you type REALLY slow.

I'll try higher octane gas and adjusting the timing table to the 2G. Though I don't think that's the problem, I am not beyond being incorrect.

Thank you for your suggestions!
 
I just put in 8.8 gallons of 91 (highest at the station...going to look for 92-93) and I reduced the timing tables to the 2G (based on those on the Wiki by ECMTuning). This made a noticeable improvement; however, anything over 30-35% and the knock retards up to 11.6 degrees.

I'll burn through this gas this week and fill up with 92-93 and see if it gets better. After that, I might adjust the timing tables a bit or adjust when the control of the knock sensor.

I guess I should stand corrected. I didn't think the 87 would be bad for a stock car with stock boost, but so far it looks like I am wrong.
 
True, I never heard of any 4g63 that didn't require premium gas. For the record I can get to 7-9 psi with 33% throttle. So you can definitely be into boost/knock risk. Also to check timing you only need to take off upper timing cover, and remove the plastic wheel well skirt on the drivers side. You'll see the crank pulley and crank timing marks. Then just insert a half inch into the crank pulley and turn clockwise until crank is at 0/tdc. You may have to go around up to 2 times to get the cam marks to line up. Realize that your cam gears are mounted at a slight angle (because the head isn't totally level) so most recommend holding up a straight edge to the cam timing marks with the straight edge parallel to the head surface.
 
You really need to check mechanical timing and base timing, if one is off it can cause knock like your getting. I would lean towards base timing being off. Cuz if your mechanical was off by more than a tooth your motor wouldn't be running.
 
First of all, not sure why you Hawaii guys have to rub it in my face by responding together and ganging on me...I mean...we have 4-6 inches of snow coming tonight (starting right now) and our high temp next week might hit double digits. :) I am a little jealous.

Base timing is right on 5* BTDC. I will check mechanical timing next time I can swap cars in my garage. Thanks for your replies guys!
 
That most certainly could not be done in the time it takes me to type this - hot or cold outside - unless you type REALLY slow.

As stated, there are timing marks on the cover which makes it really easy. Literally just line up the marks of the harmonic balancer with the marks on the lower cover (on my car I can turn the wheel and reach my arm in there with a 1/2 in socket while on the ground without taking the wheel off) and take off cam cover and look at the marks.

"yes...I have heard of timing being off causing lots of knock" or "no...timing being off a tooth wouldn't cause lots of knock." Because I don't know the answer to that, that's the type of answer I was looking to get in response.

Every car is different. There are too many determining factors. Sure, its possible. But you will never know unless you check it. While one cars timing could be off with no knock, another car could have knock.

And for all that is good in this world, please never put anything but premium in your tank again ;)
 
Update for those searching or who care: Replaced all belts, pulleys, and water pump, because the mechanical timing was off (which was much easier to actually confirm by removing the lower timing belt cover). It appeared that the intake cam was advanced one tooth too far. My part throttle knock is now completely resolved.

The idle surge is still happening. It's odd because it only does it at a specific water/air/engine temp - not cold at initial start up and not fully warmed up. And it only does it for like 60 seconds or so. This makes me think it's the FIAV but if that's the case, I have two throttle bodies with faulty FIAVs. I have yet to swap the throttle body from a known good car.
 
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