89 Toyota 4wd ext cab 22RE 135k 31's 4.10 gears
Ive owned the truck for about 2 years now, ever since ive had it, it has always spark knocked under hard acceleration. Ive tried various fuel additives, new plugs, throttle body cleaner etc. Timing was @ 5btdc with te1 and e1 bridged. I always use 87 octane, but when i did use 93 octane once, it didnt spark knock. Looking at the spark plugs there is evidence that the fuel mixture is lean. So today i experimented with retarding the timing, I had to retard it to 2btdc(te1 &e1 bridged) before the spark knock almost stopped. It is hard to tell but engine performance seems to be the same. The previous owner did have a dual row timing chain kit installed with an adjustable cam gear from LC Engineering, ive experimented with the cam gear also, still no luck. Any ideas on what is going on? Thanks for your help in advance.

Have you tried running cooler plugs. A glowing elctrode may be contributing to preignition. Did the previous owner perhaps mill the head or block causing higher than stock compression?

Ive tried 2 different types of plugs, autolite platinums and NGK R BPR5EA-L. Im currently running the NGK's. I also have a new set of Denso W16EXR-U which i havent tried yet. What sparkplugs would you recommend?
Correct if im wrong, in order for the previous owner to have put a new timing chain kit on, he would have to have pulled the head right? If so he should have had the head resurfaced right? I guess the next step for me would be to check how much compression i have in each cylinder. If the compression is higher than normal what should i do next?
Thanks for your help.

Try those Denso's, they're made specifically for imports (anyway thats what the dude at autozone said)

You do not have to take off the head to do the timing chain. To replace the chain you can just take off the timing chain cover without removing the head.

The denso spark plugs are OEM one that truck.

2 possibilities:

1. Carbon deposits causing higher than normal compression.

2. Carbon deposits causing clogged EGR passages.


For #1, use Seafoam to clean.

For #2, use carb cleaner, brushes, and pipe cleaners to clear blockages.

I was actually refering to the heat range of the spark plug and not the manufacturer of it. I have usually had good luck with NGK and Denso in Toyota trucks.

Thanks for your response.
Could you tell me what seafoam is and how i would use it?



Ive never messed with the egr system, what all would i have to do here?
Thanks for your help in advance.

Sea Foam is a multipurose engine cleaner. You can get it a auto parts stores. To clean the cylinder and valves you can put it in the gas tank. You can also put it in the oil or even inject it into the intake manifold with the engine running via a vacuum port.

for serious carbon buildup in the EGR i use oven cleaner, like easy off or something like that. drives my wife nuts cause she never has any oven cleaner under the sink. for the egr, youll want to clean the valve itself, mounted to the head behind the intake manifold, the tube that connects it to the upper plenum, take off the upper plenum itself and clean that passage with a bottle brush, and as much as you can get from the head itself.

i had the same thing happen to me once, EGR vacuum hose popped off, causing spark knock much like you are describing. my two cents