So ive been battling this engine knocking problem with my rebuilt motor for a while. Took out the thermostat to keep her alot cooler and it worked to some extent. It didnt knock as much. I had the block bored 40 over and people told me that it would run hotter but noone said anything about knocking. Well today i put the thermostat back in and i thought the engine was going to "knock" it self apart. It did it so much i barely got down my driveway and i had to back up cause it was so bad. I have my topfeed conversion done cause i thought more fuel would help but it seems to have actually worsened it. Any suggestions?


http://www.cardomain.com/ride/2090440

First off, I hope you are running premium gas, you need the highest octane rating you can get. Use an octane booster, or even better, an unleaded race gas (100+ octane rating) any time you run the nitrous.

In the photo of your head, I can see that the head was surfaced, do you know how much? Was the block surfaced also? If so, how much? Do you know what the piton-to-deck clearance is? This can increase the Compression Ratio, over the 10:1 CR that the pistons came with, which could lead to more knock. You may have to change over to a thicker copper head gasket (requires o-ringing the block) to reduce the CR, if it's too high. This may vary, depending upon the amount of piston quench you have.

Also, the cam can affect the dynamic CR, depending upon the amount of overlap (lobe centers) and the intake opening point (intake center line). Do a compression test and see how much cranking pressure you have. You should have about 180-190 psi max for pump gas (premium).

Do you have access to HPT or other data logging scanner? If so you need to get a reading of the A/F ratios, the Knock retard and spark timing. Using HPT, make any adjustments as needed.

Try using the DIS2 to retard timing a bit...



fortune cookie say:
better a delay than a disaster.

Quote:

180-190 psi max for pump gas (premium).

Not always true.

The 2.4 has 210-215 psi cranking pressure and run on 87 octane.
The Ho has 210-215psi cranking pressure and run on 91 octane.
My W41 has 265-275psi cranking pressure and run on 94 octane.

Did you mesure the pistons before putting them in? Did you bore the block BEFORE getting the pistons or you bored the block with the pistons in hand?



Gilles
2.3 Ho

question... when my eagle rods and wiseco pistons were installed they protrued the block by 8 thou... is that normal? I went 20 thou over sized with sotck length rods stock crank...

sorry to thread jack, but seems like this is a pretty good thread to ask.

And I need to check my compression I guess, cause I get hard core KR even with 91 octane, I turned off knock to see if it was fake... and it pinged.. all this at only 10psi.. and only from 5k rpm and up.. hmm


when you check compression.. you do it on a warm engine? is it a good idea to pull the plugs out with a hot engine?


HP Tuners | Garrett T3/T04B | 2.5" Charge Pipes | 2.5" Downpipe | 650 Injectors | HO Manifold | Addco front/rear | Motor Mounts | HKS SSQV | Spec stage 3 | AEM UEGO Wideband | Team Green LSD | FMIC | 2.3 cams | 2.3 oil pump swap | 280WHP | Now ECOTECED

ge_forcez22 wrote:question... when my eagle rods and wiseco pistons were installed they protrued the block by 8 thou... is that normal? I went 20 thou over sized with sotck length rods stock crank...
when you check compression.. you do it on a warm engine? is it a good idea to pull the plugs out with a hot engine?

Apparently, the Eagle rods on the OHVs are actually longer than stock (may be the same on the LD9s), and your block may have been decked during the machining maybe? As long as the rings don't come out of the block it's not a problem. However, you have to make sure you have adequate clearance between the piston and head, and piston and valves (.030" minimum to head, .040" minimum to valves with the forged rods and pistons), you may have to get a new headgasket for clearance. You also have a higher CR with the longer rods, wider bore, and possibly lower deck.
And yes, warm engine.



fortune cookie say:
better a delay than a disaster.

yah, I am almost thinking tht my compression might be too high if in fact the rods are too long. I need to check a compression, I have 12k miles on my engine and I can't figure out why I have a misfire. Maybe I will rip it donw and put a thicker cometic gasket in.. .*sighs* but I have a MSD 6212 I am going to try first.


HP Tuners | Garrett T3/T04B | 2.5" Charge Pipes | 2.5" Downpipe | 650 Injectors | HO Manifold | Addco front/rear | Motor Mounts | HKS SSQV | Spec stage 3 | AEM UEGO Wideband | Team Green LSD | FMIC | 2.3 cams | 2.3 oil pump swap | 280WHP | Now ECOTECED

ge_forcez22 wrote:yah, I am almost thinking tht my compression might be too high if in fact the rods are too long. I need to check a compression, I have 12k miles on my engine and I can't figure out why I have a misfire. Maybe I will rip it donw and put a thicker cometic gasket in.. .*sighs* but I have a MSD 6212 I am going to try first.

the compression will not cause the missfire, may cause the knock but to be honest with you i would get the missfire iron'd out before going into detail about the knock, Try out the 94 Mohawk on the car and see what that does knock wise, or if you want i can hook you up with some unleaded race gas.

i wouldnt go jumping into crazy work like doing headgaskets etc right away, look at the more simple things first.


_______________________
** Flat Broke Racing Inc.**

I have about 4 little things I am going to try, and if none of them work, them I am looking into headgaskets and such... but when I do a head gasket I will have to replace my head... oh well.


HP Tuners | Garrett T3/T04B | 2.5" Charge Pipes | 2.5" Downpipe | 650 Injectors | HO Manifold | Addco front/rear | Motor Mounts | HKS SSQV | Spec stage 3 | AEM UEGO Wideband | Team Green LSD | FMIC | 2.3 cams | 2.3 oil pump swap | 280WHP | Now ECOTECED

The high compression can possibly blow out your spark and cause a misfire, try gapping your plugs a little tighter.



fortune cookie say:
better a delay than a disaster.

^ God thank you for the tip. I'll try that with mine. I have an horrible misfire on startup. It's running on 3 and has one hell of a hard time to gewt on 4. Misfire too when on 4.



Gilles
2.3 Ho

a larger gap will make it run better at idle.. if you have the heat for it. I will be trying that MSD, as we think I am getting blow out, tight gapping is just a bandaid for an underlying issue.

my plugs are 28 thou now, and I will gap as tight as 18 thou when I get home with some new plugs to see if that fixes the issue, if it does then I will go full MSD ignition.


HP Tuners | Garrett T3/T04B | 2.5" Charge Pipes | 2.5" Downpipe | 650 Injectors | HO Manifold | Addco front/rear | Motor Mounts | HKS SSQV | Spec stage 3 | AEM UEGO Wideband | Team Green LSD | FMIC | 2.3 cams | 2.3 oil pump swap | 280WHP | Now ECOTECED

OHV notec wrote:The high compression can possibly blow out your spark and cause a misfire, try gapping your plugs a little tighter.

but that is a great idea that was not previously mentioned, thanks man



HP Tuners | Garrett T3/T04B | 2.5" Charge Pipes | 2.5" Downpipe | 650 Injectors | HO Manifold | Addco front/rear | Motor Mounts | HKS SSQV | Spec stage 3 | AEM UEGO Wideband | Team Green LSD | FMIC | 2.3 cams | 2.3 oil pump swap | 280WHP | Now ECOTECED

ge_forcez22 wrote:a larger gap will make it run better at idle.. if you have the heat for it. I will be trying that MSD, as we think I am getting blow out, tight gapping is just a bandaid for an underlying issue.

my plugs are 28 thou now, and I will gap as tight as 18 thou when I get home with some new plugs to see if that fixes the issue, if it does then I will go full MSD ignition.

With higher compression and boost, tighter gapping will be necessary. An automotive ignition system can only accomplish so much, eventually you have to lower the gap (which is obviously bad for other things, such as the flame speed and complete burn).
However, .028 should be small enough for what you have, any smaller should not be necessary.



fortune cookie say:
better a delay than a disaster.

The stock ignition system produces enough voltage to fire across a .060" plug gap in series with a spark tester requiring 35kV to arc. It would take quite a bit of compression to "blow out" that spark at idle if the ign system is in good shape. IIRC the GM DIS is able to provide 60 kV or more depending on the year and design of the individual system. 60 kV is enough to generate arcs almost 1" long.

Both Q4 and 2.2 L engines can benefit from some diagnosis in looking at dead cylinders. Either buying a spark tester or making one, and placing it in series with each plug, one at a time, can give a very good indication of whether or not there is sufficient voltage at the plug to start ignition. Making a tester isn' t a huge deal. You open a spark plug gap to .100 inches. The real trick is finding a way to connect the tester in series with the plug without allowing spark to "leak" to ground. When done right you'll be able to easily see whether the spark at the tester is present every time the ignition system fires.

A warm engine at idle can give other clues as to how a cylinder is dead. Running the engine for a short time then removing the plug should reveal a plug which is wet or dry, and has a color ranging from black to normal brown. A dry cylinder may have too little fuel, an intake valve not opening, or just very low compression. A wet cylinder may have oil leaking in, excess fuel, or insufficient spark. A vacuum gauge can also be a very effective tool in diagnosing misfire. Gauge readings should be consistent as the engine runs. Larger cammed 4 cylinder engines may cause the gauge needle to cycle, but the values should be the same for all 4 cylinders.

You really shouldn't need to drop plug gap below .028" imo. I wouldn't expect anything below .030"with OEM DIS.

-->Slow

So i took out my thermostat tonight and the car ran great! Its deffinantly a heat problem... I dont know where to go from there...


http://www.cardomain.com/ride/2090440

Didn't you say it was knocking before it left the driveway? How long had it been running?



fortune cookie say:
better a delay than a disaster.

it sounds like your pistons are expanding too much when heated up. And could be coming in contact with the cylinder walls. I know when i was bulding my enine Jasmin and I kept a close eye on the silicone content in the pistons because more silicone means more expansion....



LE61T PTE6262 Powered

i dont like the looks of this nate.... get it fixed.

ive had the head off numerous times and there is no way the pistons are hitting the head. theres plenty of clearance. I did the clay test for the valves and piston to head clearance when i was building it. I think the problem is that it is bored over too much and its getting super hot with the thermostat in. Could more fuel also help knock? Ive heard that more fuel in a engine will actually have a cooling affect.


http://www.cardomain.com/ride/2090440

Its really worrying me cause im like out of options...


http://www.cardomain.com/ride/2090440

1) my pistons came over the block 8 thou, no issues there
2)heat does cause detonation.. not sure but 98 uses a different head gasket then 99, I assume you are using a cometic... compare it (picture wise hopefully) to a stock one.. make sure the coolant passages are all the same
3)lean?? either FP or clogged injectors
4)plugs

pull oil pan check for
5)loose connecting rod...
6)spun bottom end bearing
7)missing main cap and or main bolt
8)oil pump
9)oil pump drive gear


another thing.. did you use stock crank and rods length.. what if a rod is hitting the cylinder wall... or a bad map sensor... hmmm. TPS....ummm..... try a different ICM/coilpack/boots

thats all I got hopefully I gave you a new idea or 2,


HP Tuners | Garrett T3/T04B | 2.5" Charge Pipes | 2.5" Downpipe | 650 Injectors | HO Manifold | Addco front/rear | Motor Mounts | HKS SSQV | Spec stage 3 | AEM UEGO Wideband | Team Green LSD | FMIC | 2.3 cams | 2.3 oil pump swap | 280WHP | Now ECOTECED