|
| Windza |
|
|||
|
Guys, just bought a 98" NL Fairlane with the 5.0L (or 4.9...whatever) V8 and have noticed it will miss very slightly when you let the revs die back from anything above idle and goose it. It also blows a fair bit of black smoke when it happens. I'm not sure if the miss is to do with overfueling or lack of spark. Normal driving seems all ok. I have replaced the spark plugs and leads to no avail, opened air box for more air and nothing works to get rid of it. Does anyone have any suggestions...I suspect it could be the TPS or MAF or even coil ? I'm about to do a few EEC tests and see if anything comes up...will write if anything shows up...thanks
|
|||
| Top | |
|||
| 4.9 EF Futura |
|
|||
|
Hey there windza
Congrats on the purchase. Have you checked out the MAF sensor and the two wires which are inside it? If too dirty, these can be cleaned (i think carby cleaner and cotton tip is the preferred method). This will allow the ECU to better meter the amount of air entering the engine.
_________________ I promise..... I will never die. |
|||
| Top | |
|||
| Vic |
|
|||
|
Does the engine seem to surge / hunt a little, when you brake to a stop at an intersection?
_________________ 5.6L of carbon footprint. |
|||
| Top | |
|||
| Bsjenko |
|
|||
|
vic.... what would that mean? my cousins car does that....
_________________ The Lane Lives.... Finally!!!! |
|||
| Top | |
|||
| Windza |
|
|||
|
Thanks for the quick replies. Vic, I haven't noticed the car surging or hunting significantly....BLWN-49, I just cleaned the MAF sensor (only slightly dirty) as suggested and it has made no difference...although I did start the car without the sensor connected and didn't really notice much difference either. I'm not sure what the ECU does if there is no input from the MAF, I guess it just estimates values from the computer? I would've thought the car should still run reasonable without the MAF though...I just think the miss might indicate something a little more than a sensor...Ford suggested the coolant temp sensor but how that would make it miss has me beat.
Does anyone have values (resistance or whatever) that the TPS should return ? |
|||
| Top | |
|||
| EDXR8 |
|
|||
|
TPS isn't used all that much by the EEC and probably wouldn't cause those problems but at closed throttle the TPS should be outputing under 1v (0.9-0.98 normally) and should go to around 4.5v at full throttle. I would firstly make sure your ignition system is in good condition (plugs, leads, dizzy cap and rotor) and that your base timing is set properly and check the fault codes on your EEC, that should tell you if any of the sensors are stuffed. After that I would look at O2 sensors which may be causing rich/lean idle/closed loop conditions. Without the MAF connected, the engine should run but it will be very rich with limited timing advance, which gives very poor performance and economy but it is safe at least.
|
|||
| Top | |
|||
| Windza |
|
|||
|
Thanx EDXR8, the o2 sensors were my initial thought but after talking to the auto lecky about getting them tested he said that they only get used by the ECU when it detects the car is moving...I'm not too sure how true this is but it would rule them out for the problem I'm having at the moment...I have replaced leads, plugs and cleaned the dizzy and rotor and it made no difference. I will check the TPS now and run the EEC tests... see what happens...hmmmm...
|
|||
| Top | |
|||
| Vic |
|
|||
|
When I bought my car, it was running quite lean which I noticed when I put the boot in and it pinged under heavy load. I had it dynoed and they found the MAF was stuffed. I bought a reco'ed MAF and that fixed it.
_________________ 5.6L of carbon footprint. |
|||
| Top | |
|||
| Windza |
|
|||
|
Alright...did the tests and initially the KOEO test showed the MAF shorted to ground (Memory code) which would've been when I started the car without the MAF connected, so I reset the code and then performed the tests again. Both tests returned 111 so I guess all the sensors are returning correctly...where to from here? Maybe all the 5.0L do this ?
|
|||
| Top | |
|||
| EDXR8 |
|
|||
|
{USERNAME} wrote: Thanx EDXR8, the o2 sensors were my initial thought but after talking to the auto lecky about getting them tested he said that they only get used by the ECU when it detects the car is moving...I'm not too sure how true this is but it would rule them out for the problem I'm having at the moment...I have replaced leads, plugs and cleaned the dizzy and rotor and it made no difference. I will check the TPS now and run the EEC tests... see what happens...hmmmm...
Its worrying when so called professionals give out bad information, the O2 sensors are used when the car is idling and during medium-light throttle application and cruising ie. when the EEC is in closed loop fuel control. If they are getting old they can sometimes make closed loop AF ratios a bit unstable or constantly lean or rich. A bad o2 sensor may give you the symptoms you are having but its probably a long shot, a dyno with wideband o2 reading should show you whats going on. When you say it misses when you let the revs die down and goose it, what do you mean? and does it happen when driving or just when idling out of gear? |
|||
| Top | |
|||
| Windza |
|
|||
|
Ok...I'll describe it in detail if I can...I bring the revs up to about 1800-2000rpm slowly from an idle...everythings ok, no miss or hesitation....then completely release the throttle, if you then open the throttle quickly (to around half throttle) as the revs fall back to about 1000 rpm it will miss on maybe one or two cylinders before picking the revs up. It gives a puff of black smoke at the same time. For normal operation of the car you probably wouldn't notice it...sometimes I think I can feel it just pulling away from an idle at a stop sign, but you can't really be sure because it seems to do it only for a split second. One thing I forgot to mention is that it seems only to do it when warmed up...which may indicate O2 sensors...what I might try is disconnecting the O2's (assuming this will put it into closed loop) and seeing if it still does it...?
|
|||
| Top | |
|||
| EDXR8 |
|
|||
|
Wouldn't disconnect the 02's the EEC wont like that at all.
What you are describing does not sound that abnormal, when you hit the throttle quickly the AFR normally goes a touch lean (maybe around 15:1) and then stays at 14.64 for 2-4 seconds to save petrol. This lean condition on initial throttle isn't great for pickup and can cause a slight miss but it is good for petrol and thats why it is programed that way. But if your O2's or anthing else is already causing a slightly lean closed loop, then it may just go too lean on initial throttle, but thats just a guess you will need a wideband or syno to confirm it. |
|||
| Top | |
|||
| Neal-50 |
|
|||
|
i would also sugest looking at injectors, how many ks has the car done, my nf had a similar fault which was a combination of dirty injectors and dirty Maf. Try a bottle of Nulon Fuel system Cleaner. The best way of cleaning the injectors is of course to remove and ultrasonicly clean them but i have had good results with the nulon product, so try that first.
_________________ Pround memeber Team DYNAMIC WHITE
|
|||
| Top | |
|||
| Timmeh |
|
||
|
{USERNAME} wrote: Ok...I'll describe it in detail if I can...I bring the revs up to about 1800-2000rpm slowly from an idle...everythings ok, no miss or hesitation....then completely release the throttle, if you then open the throttle quickly (to around half throttle) as the revs fall back to about 1000 rpm it will miss on maybe one or two cylinders before picking the revs up. It gives a puff of black smoke at the same time. For normal operation of the car you probably wouldn't notice it...sometimes I think I can feel it just pulling away from an idle at a stop sign, but you can't really be sure because it seems to do it only for a split second. One thing I forgot to mention is that it seems only to do it when warmed up...which may indicate O2 sensors...what I might try is disconnecting the O2's (assuming this will put it into closed loop) and seeing if it still does it...?
That sounds exactly like what my EL XR8 did. Normal driving and it was good but giving it a little it missed and shuddered. Mine was an ignition lead that had split and burnt on the extractors, plus they were the original 1997 leads. I replaced mine with Bosch Super Sports leads and all was better. I know you said you replaced leads but I would check the number 4 lead connection to the plug because that is the hardest one to get on for me. What leads did you use to replace new or old and what brand? |
||
| Top | |
||
| Windza |
|
|||
|
Spark plugs were NGK (on recommendation) and bosch "super" leads. I made sure they were all on right when it still had the same problem after replacing them. I've had a few people tell me that the "problem" may be just something that all the standard 5.0L's do...maybe they're right, it's just annoying because I really didn't think any fuel injected engine should miss under any circumstance...?
|
|||
| Top | |
|||
| Who is online |
|---|
Users browsing this forum: No registered users and 20 guests |
