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Discussion Starter · #1 · (Edited)
Hi Guys, pretty new to the forums here and couldn't find anything related to my issue. I have a bone stock 95 XR7 cougar that was throwing the P1407 code. I have emissions testing coming up soon so I decided to attack the problem by throwing a new DPFE sensor on the car and driving off happily into the sunset. Well upon test driving the car I noticed the idle was now very rough and I can hear an intermittent knock on the passenger bank. At first I thought I had installed the intake elbow incorrectly and caused a vacuum leak. Re-installing the elbow after a good sanding and new gasket did not solve the problem, only during this test run I happen to notice the ignition advance is at 22 degrees just idling in park on the driveway. I thought perhaps the cam position sensor was bad, unplugging that did nothing. The IAC seems fine because unplugging that also changed nothing. Re-installing the old DPFE sensor made no change either so my thoughts now are that a bad timing chain guide is causing the cam to rotate out of time, but I didn't want to tear that far into this without hearing out some other possibilities. Please advise, thanks Y'all!
 

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An EGR valve that's stuck open will cause a rough idle as they are supposed to be closed at idle.

Pull the vacuum hose off the EGR and see if the idle improves. Of course, plug the vacuum hose so there isn't a vacuum leak, which would cause it's own kind of rough idle. A golf tee works well to plug a hose.

Al
 

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Discussion Starter · #4 ·
Update: EGR valve holds a vacuum and activating it with a vacuum pump with the car running shows that the passages are unclogged. Changed the IAC valve which helped but didn't solve the problem. cleaned and re-gapped the plugs: again it helped but no solution. Time to get behind that timing chain cover...
 

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What's the vacuum reading on the manifold?

Is there a pulsation that goes with the stumble?

You may have knocked a spark plug wire loose, and it's misfiring occasionally.
 

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To add: if you go to the trouble of pulling the plugs, just replace them with factory ones. By just cleaning and re-gapping, you didn't eliminate the plugs as a possible culprit. Besides, nothing runs better than a car with a fresh set of plugs.

Al
 

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Discussion Starter · #7 · (Edited)
I read that the oil filter for these engines is designed with an anti drainback valve to keep oil in the timing chain tensioners after the engine is shut off. Well when I bought the car and changed the oil I found that the filter that was on it was completely wrong. Way too small and Was the wrong part number. I could have continued to run the car to retrieve more codes but was afraid of causing further engine damage. The one plunger looks like its been over extended recently, but its a 400$ timing set. Wanted other opinions before moving forward. Is it typical of these engines to have the passenger tensioner extended further than the driver side?
 

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LOOK for a vacuum leak, if it is not obvious to find use a propane torch not lit but open ,engine should perk up if there is a leak.

fuel trims with adaptive learning could pull 20 dregrees once in a while but should not be steady!
 

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I read that the oil filter for these engines is designed with an anti drainback valve to keep oil in the timing chain tensioners after the engine is shut off. Well when I bought the car and changed the oil I found that the filter that was on it was completely wrong. Way too small and Was the wrong part number. I could have continued to run the car to retrieve more codes but was afraid of causing further engine damage. The one plunger looks like its been over extended recently, but its a 400$ timing set. Wanted other opinions before moving forward. Is it typical of these engines to have the passenger tensioner extended further than the driver side?
not an issue for these engines not to be equal on the adjusters. hey at least you have the good cast iron adjusters and not the plastic ones. these lock out themselves or self ajust and don't loose tension if they are working properly... it is not the oil filter that keeps these adjusted. its the locks inside the adjuster.

if you don't have good oil pressure they will not self adjust.

also since it is this far apart here is a link for timing chain installation. without taking it apart line up the marks on the timing chain with the guide I provide.if the marks are in sink your good its not a problem
http://www.jegs.com/InstallationInstructions/300/397/397-M-6004-462V.pdf

a decent chain set can be purchased on ebay for under a hundred if you need one. http://www.ebay.ca/itm/Timing-Chain...ash=item565d084326:g:BkMAAOSwC9VZgsrv&vxp=mtr
 

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Hi Guys, pretty new to the forums here and couldn't find anything related to my issue. I have a bone stock 95 XR7 cougar that was throwing the P1407 code. I have emissions testing coming up soon so I decided to attack the problem by throwing a new DPFE sensor on the car and driving off happily into the sunset. Well upon test driving the car I noticed the idle was now very rough and I can hear an intermittent knock on the passenger bank. At first I thought I had installed the intake elbow incorrectly and caused a vacuum leak. Re-installing the elbow after a good sanding and new gasket did not solve the problem, only during this test run I happen to notice the ignition advance is at 22 degrees just idling in park on the driveway. I thought perhaps the cam position sensor was bad, unplugging that did nothing. The IAC seems fine because unplugging that also changed nothing. Re-installing the old DPFE sensor made no change either so my thoughts now are that a bad timing chain guide is causing the cam to rotate out of time, but I didn't want to tear that far into this without hearing out some other possibilities. Please advise, thanks Y'all!
what was your idle speed ?
 

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Sorry to bring up a dead page, but was this issue ever resolved? I have the exact same issue going on. Thanks!
 

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The real issue is the egr tube is clogged, most likely.

Carefully disassemble the egr tube; the egr flow is across two ports installed into the egr tube from the exhaust, that are ran to the sensor.

Short answer; if the egr tube orifice, that is welded into the egr tube between the sensor tubes, gets clogged, it reads wrong.

Fix is to clean the egr tube.

Dont break it, they do not exist, iirc.
 

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Sorry to bring up a dead page, but was this issue ever resolved? I have the exact same issue going on. Thanks!
Any chance we can get the year and model of your car, and engine? Put it in your info so it shows up under your name.

Assuming you are talking about a 94-95 4.6, the plenum and intake manifold under the throttle body is first thing to clean. It takes some time to clean it all out. I did that on my old T-Bird at around 150k. The EGR tube didn't clog shut until 220k.

Al
 
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