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Hello all, my name is Tim Braloski and I this is my first real post here so please be patient. I have a 94 f150 with the 4.9l and E40D auto trans. It has AC and is 2whl drive. My problem is this. I had severe spark knock about a year ago and decided to rebuild the engine (almost 200k). Head was in great shape however there was slight scoring on cylinders so pistons were part of the rebuild. rebuild went well however, and needless to say, I still have severe spark knock at idle. timing hovers between 4 btdc and 0 degrees. The MAP sensor tested good using a vacuum pump and a digital tach on meter. it went from 320 rpm at 0 inches vac to around 190 at 22 inches. There is good vacuum at idle ..or I think there is, its 20 pounds but drops to almost 0 as it surges. i checked all components that use a vacuum sorce for leaks and even bypassed them and same condition still occurs. I am currently bypassing the "vacuum cannister" as it was leaky. i will make a new one tonight out of 3" pvc.
The EGR vacuum solenoid was bad, the coil never activated, so it was replaced. I am not even sure it is coming into play.
I ran the DLC test for EEC-IV codes and here are the codes i retrieved.
KOEO test 33 and 133. KOER test gives 532, 536, 538.
if I unplug a vacuum manifold port the engine will idle but timing still sits aroun 4 dbtdc and 0. and of course engine gets hot. i get spark knock bad so i cant run the engine very long.
fuel pressure is 50 static and around 42 with engine idling.
I will do more electrical tests later. there are a lot of checks for the EEC-IV that are manual, I guess I will go through them later.
Any advice as to what to check would be appreciated.
Thanks so much, Tim
One Question I have is, does that timing seem correct? This is my first time troubleshooting an engine that is having such a problem with non adjusting timing. Cam and Crank were correctly aligned and i had 1 at TDC when I dropped the distributor in and aligned to 1.
Can't help ya much.. perhaps the balancer has slipped and not seeing correct timing. Can you retard your timing and the engine straighten out..no matter how far, but does it get better? Is the PCM correctly advancing the spark when you pull the Spout and insert it back in?
thanks timbersteel, I am not very familiar with SPOUT CONNECTOR, I will find it and disconnect and try to manually adjust the timing. That is pretty good about the timing mark on the balancer, but the balancer was pretty much like new. so i will find and pull the SPOUT, would you know should i go with about 14 btdc? thanks so much.
I didn't clarify my first statement in regards to the Spout Tim. With the Spout connector removed, the PCM doesn't control spark advance. If, for example, everything was running ok and you were using a timing light, you should be 10 BTDC with Spout connector removed and when you insert it back in, the timing would advance up to around 18-22 BTDC.
Sorry for my mistake earlier on the function of the Spout.
thank you. I pulled the grey plug and adjusted timing from 0 to 12. idle is smooth now, but under load still get knocking sounds. that is even in gear it gets knocking sound. I put it in gear and hold the break, when i accelerate slightly, i get the knock, the same knock as before the engine rebuild. I pulled the codes again and get on the koeo test, 33,334,334
on koer I get, 538,536,632. that repeats twice. I pulled the negative battery cable to reset and will try again later. Thank you for the input.
334 is stating that the EGR closed valve voltage high.
The other listed codes really only point to 538-operator not performing goose test, 536-Brake on/off circuit not activated during KOER, 632-Overdrive Transmission Cancel Switch/no action during self engine run test.
let it sit for 15 minutes with battery disconnected. Reconnected and engine started right up. at idle it sounds good but seems to be running rich as it smells rich. it was not like that at all during last weekend tests, if anything engine was running lean and hot. Timing is at what looks to be 20 degrees btdc and holds very stead at idle. engine definitel running rich now, i smell it. getting 33 and 33 now for KOEO test.
"Spark knock" at idle is unusual. Especially with the timing and vacuum numbers you're reporting. Are you sure it's spark knock and not a faulty torque converter or some other accessory/ pulley/ belt? ~Bill
thanks Timber and Bill, I am not 100% sure its not a torque converter Bill, but the noise seems to be coming from the middle of the block, like in the area just to the firewall side of the distributor, just under the side access cover, but again, i am not sure. I will put a stethoscope on it tomorrow and try to isolate better. It has ne lifters and cam shaft and I preloaded the lifters. I installed new pushrods and rotated the engine 120 degrees at a time to torque the rocker arm nuts. Rocker arms were put in original positions. I installed a high volume pump and put a mechanical gauge on it. (cold idle about 48, drops to 42 once warmed) Main bearings and rod bearings were plastigauged and had correctl clearance. block, crank and heads were prfessionlly serviced. Also put a new oil pickup and tube on it. I have 18.5 inches of vacuum now, motor idles well, but runs so rich you can smell the gas and see it in exhaust. I will try to isolate the noise better. The air pump is noisy, but its a seperate noise, i think its just the way it works but not sure.
I am sure I have good seals, I can give the compression if that would help, but am sure its good. i will put the pressure gauge back on and give a reading on the fuel rail also. Anything else that would be useful to you all, let me know. Thanks for the advice. I will drive it around for a while to see if it gets better, but I am a little concerned about the knock, dont want to ruin what I just put in. Do you know, is there a gas additive I can get to raise the octane a little or is that not recommended. Same question with plugs, is there a recommended set of plugs?
I am not sure abou the O2 sensor, the TPS, the EGR valve itself,
How old is the O2 sensor? If more than 3-4 years old with many miles, could use a new one. If after the engine has ran for at least 15 minutes, you can chec. For stored codes. I would be inclined to purchase the EQUUS CODE reader now and let it take some guess work out. I didn't ask if you have that already. It's a nice piece of equipment to have if you plan on keeping the truck.
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