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Engine knock (code 304)

05-20-2005, 09:25 PM
Just joined the forum today.

I have a 1999 Windstar that I bought for my wife used in ’01 with 28k miles. Today she’s pushing 98k. Up till two days ago, I didn’t think that I had ever had any problems. After reading the forum a couple days, many things have become clear.

About two years ago she started “pinging” at acceleration. Detonation I figured, so I had my wife move up a grade on the gas. Today (thanks to all of you), I suspect that the problem was actually the faulty rocker cover allowing oil into the intake tract.

Couple of months ago, the check engine light came on. So I bought an OBD II code reader. She had a 171 code (again, this was pre-forum). So cleared the CEL, and it never came back on. I figured dirty injectors, ran a bottle of cleaner through and told my wife to stop buying gas at the discount place down the road.

This past Wednesday she called me at work to say that there was a big problem. Barely running to the point of almost stalling, and a very bad “knock” in the engine. Checked the codes. Had a 304 with a 171 pending. While searching the net, I stumbled upon you fine gentlemen (yeah, I’m trying to butter y’all up).

Anyway, read what you guys had to say. Pulled the #4 plug for the 304 code. It was original, and the gap was out to .070” with age. Other than that, they didn’t look real bad. So I bought plugs and wires, hoping that because 4 was misfiring (and dumping un-burnt fuel), the computer was leaning out bank 1. I know, but you can always hope right? So replaced ‘em all, but it didn’t help much. I cleared the codes and checked again. Now the 304 is pending, and there’s no sign of 171. But the engine is still knocking.

When I started her up after the plug change, had a bit of fluid come out the tail pipe. Also appears to be some steam. Never really noticed it that much before, but my wife drives her most of the time.

Using a long screwdriver as a stethoscope, the “knock” is strongest in the area of #4 intake port. Cannot hear it in the block or head areas. You know it almost sounds like a header exhaust leak. I tried tugging and pressing on the intake (per forum suggestions) and it does not appear to be an internal baffle loose.

Well that’s about everything. Sorry for the novel length post. I guess I should just bite the bullet and start tearing the intake off? Could leaks around the intake seals and those support bolts make the engine knock? What are the odds that the head gasket is also shot?

Any feedback would be appreciated.

05-20-2005, 09:43 PM
You probably just have a case of bad pre-ignition. Unless the engine has seen severe overheating, the heads and gaskets are OK.

You didn't mention any coolant loss ....???

So, I'm going suggest that you go ahead and jump into the upper intake manifold repair. Your Winnie is at the mileage where the problem will show up. The job is not that big or expensive .... except for the isolator bolts, and with a bit of shopping you should be able to buy them for $6 x 8 at a Ford dealer. I'm guessing $75, or so, for gaskets and all. You will learn about the IMRC and the EGR jets all in the same job. .... and feel so good when the job is completed and the Winnie is running good again.

If you do have coolant loss, you may want to consider adding the gaskets on the lower intake manifold .... a heck more work.

05-21-2005, 06:35 AM
Thanks a bunch 12ounce (I have read a number of your other posts elsewhere in the forum). I’ll give the intake repair a shot. I just didn’t want to get it all back together and find that the HG was bad also. I did headgaskets three times on my Mustang last year, so I’m a little sensitive about that now.

05-21-2005, 09:13 PM
From what I have read....the lower intake manifold gaskets are a higher failure item on the post '95 windstars as compared to the head gaskets.

It is normal for some water to drip out of the exhaust pipe just after being started....more so in cold weather. Once the exhaust system warms up....the moisture stops condensing in the exhaust system. Water is THE major product of combustion. It is understandable to be sensitive to ANY steam and water coming out the tail pipe.

05-22-2005, 01:23 PM
I have the intake off. The whole thing was covered in oil inside. The recessed areas where the isolator bolts are located were filled with oil. The was also oil on the top of the lower intake, I assume from where it had leaked around the isolators. Going to the dealer tomorrow to get the required TSB repair kit.

Hope this fixes it!!

05-22-2005, 08:16 PM
It's quite normal for that area to be oily ... and yes, the oil will break down the rubber on the original design isolator bolts. (All that oil is the result of a very effective PCV system ... its keeping the inside of your crankcase clean of piston blow-by ... don't fight it.... as some do!)

How are the EGR ports? Surely a couple, or more, are plugged!

05-23-2005, 06:19 AM
Close to plugged, but not all the way closed off. They're cleared out now!!

05-23-2005, 08:53 AM
Has the DPEF sensor been upgraded? ... would be black plastic.

05-24-2005, 07:11 AM
Late start lastnight. Got the intake back on and everything hooked up (or at least I assumed everything). She just barely started. I had to put the gas peddle to the mat to get her going, still knocked on cylinder 4. Didn't idle. I figured I had a vacuum leak somewhere, but it was 10:30 so I called it a night.

I bought the van with less the 30,000 on it. This is the first problem I've had.

At te risk of sounding dumb, what's the DPEF sensor and where is it located?

05-24-2005, 08:00 AM
Huummm.... No, I have not replaced the Differential Pressure Feedback Electronic sensor. Is that another high failure item?

05-24-2005, 10:04 AM
Bet you will find a hose not connected.

Yep, the DPFE sensor is a high failure rate item, ...also a high cost item. It will eventually give a code if it is beginning to fail.

05-24-2005, 08:05 PM
The DPFE is an easy item to replace.
I have it identified in one of my pictures at

Pictures are from my '96... and my DPFE is metal....but the location is pretty much the same.

I replaced a metal one made by GP Sorenson at Advance Auto. Was not real expensive....

05-24-2005, 08:54 PM
OK. I don’t have the lower intake all the way off, but it’s looking like a collapsed lifter.

I checked all the hoses, all where good. Removed the upper intake and checked all the gaskets/seals thinking that one of them may have been pinched. All OK. Put everything back and started again. Same thing, although now the P304 was pending. Yanked the valve cover off and the rocker on #4 intake was rattling around.

Boy I’m glad it was the front and not the back. Once I get all the way in I’ll let you know exactly what the problem was.

05-24-2005, 09:03 PM
Hi Enodllew,

Welcome to the forum. The DPFE is easy to replace but I would not bother until it gives the code. I think it takes 15 minutes to replace. A while back I posted some tests for the DPFE if (when?) you get the codes.

BTW I hope the Stang is a 5.0. I have an 86 and because of it I will love Fords until the day I die.

05-25-2005, 08:24 AM
Thanks DRW1000.

Yeah, my Stang is an '89 5.0, or actually was. Is't halfway through the process of becoming a 5.4 (stroker kit). So every bit of shelf and bench space is currently covered by Mustang parts. Now I have Winstar parts scattered on top of that.

You know, this van lifter could have waited about two weeks to south and I would have been a little less bummed (LOL).

05-31-2005, 06:55 AM
Broken valve spring (intake #4) and not a collapsed lifter. Luckily I discovered that before removing the intake.

The guy behind the counter at the local Ford dealer says that this is not a common problem. However the replacement spring was of a different design than the original. They usually don't change that stuff unless they have a reason.

05-31-2005, 10:39 AM
Read all replys to your problem. I'm a little lost at this point. Was the knocking caused by the broken valve spring. I have a knock also. Not sure if it is spark knock or something else. Almost sounds like a bad piston but it doesn't smoke and the compression is fine. Just wondering if it may be the valve or spring. It sounds more internal then a push rod hitting cover. It's not really consistant and doesn't knock at low rpm's but usually a lot at higher rpm's. Thanks if you can help

06-01-2005, 11:28 AM
Mine started out as almost a "miss" at all RPMs. Luckily it broke only a mile or two from home, and my wife had the good sense to bring her straight home.

I changed the plugs and did the TSB. Still "missed" but now worse. In hindsight, it was probably getting worse because as the engine ran, the two broken coils were winding down together and the valve was no longer sealing.

Mine did finally start sounding mechanical after a while. Still sounded more like it was coming from the intake rather than the head though.

I am sure that if my compression gage had fit, that the compression on #4 would have been nill.

06-01-2005, 12:08 PM
Thanks for the reply. Doesn't sound like we had the same problem. I did read on here that it may be carbon build up. I guess ford came out with a couple of chemicals at $4.00 a bottle to run through intake and it may clear it up. I'm going to try that.

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