Ping, surging, revving?

trinogt · Apr 7, 2009

Ok, no codes... Cleaned MAF and IAC. The engine has an off-idle ping, but not under heavy acceleration. Just at cruise speed, touching the pedal ever so slightly will cause ping. Also, changing gears when engine is warm, as soon as I step on the clutch, engine speed spikes up, even during downshifts. Makes it harder to shift right. Maybe cleaning IAC isn't enough? Replacement time for it? 1998 B2500, 5 speed manual.
I ran Sea Foam through the crankcase, and almost half a bottle through intake (via brake booster hose). I am running midgrade fuel now, but still get that ping at the same time. EGR is closing, as idle is smooth. I can draw vacuum and idle gets rough, so it is functioning. Not sure if it opens at speed like it's supposed to, and I know that can cause ping, because the EGR allows more ignition timing, but that condition should be more evident under load...
Any ideas, anyone? In another post under HVAC, the engine doesn't 'seem' to warm up according to the dash gauge. May have to install aftermarket, or watch live data on my scan tool as I drive.
I am new here, and so far, the help has been fast and good!

Mark

dmassey · Apr 7, 2009

Have you checked the Coolant Temperature Sensor. They don't always throw a code when they go bad but when they go bad, they can cause problems through the entire fuel injection system. Not sure what the resistance readings should be for yours but on my 94 with the engine cold it should be around 40K ohms and when hot it should be around 3K ohms. That's how I discovered mine was bad - no code just bad resistance readings. I had checked the other items that could cause the idle problems, surging and pinging so I cheked the CTS and found it to be bad. Picked up a new one at Advance Auto for $14.99 and all is well with the world again. Hope this helps.
Danny

trinogt · Apr 8, 2009

I think you mean the ECT (Engine Coolant Temperature) sensor?
I tried to get it from Advance, and they didn't have a listing for it. I changed the temp sending unit when I did the thermostat, but could not get the ECT from them... Should I try Autozone? I suspected that sensor from the start, but could not understand it's unavailability...

locovaca · Apr 8, 2009

http://shop.advanceautoparts.com/webapp/wcs/stores/servlet/product_Coolant-Temperature-Sensor-Factory-Air_18890898-P_290_R|GRPSENSAMS_613326639___

If that link doesn't work, part number 36407

dmassey · Apr 9, 2009

trinogt said:
I think you mean the ECT (Engine Coolant Temperature) sensor?
I tried to get it from Advance, and they didn't have a listing for it. I changed the temp sending unit when I did the thermostat, but could not get the ECT from them... Should I try Autozone? I suspected that sensor from the start, but could not understand it's unavailability...

Went to the Advance website and this is the part number that came up when I entered your vehicle info: WT3058Z. Hope this helps.
Danny

trinogt · Apr 11, 2009

Funny, I see the part on the website, but when in the store, they told me they couldn't even order it?!
That's whack...
I'm gonna check resistance when cold, and again when hot, and also run live datas on my scan tool to see what the temp is reading. I will report back. I know that somewhere, there is a problem. I forgot to mention that I also get surging when driving. Not sure if that is relevant or not... Also, I tested fuel pressure when running (idle) and it is a solid 64 psi. Is that normal? I tested twice and got the same result.

trinogt · Apr 11, 2009

Ok, checked resistance cold and hot:

Cold, I got a reading of 3000 ohms. Hot (184 degrees indicated) I got 153 ohms.

Now, according to this site http://www.freeautomechanic.com/ect3.gif
chart, cold should have been around 24,000 ohms, and hot between 2000 and 3000 ohms. That means my sensor is way out, right?

locovaca · Apr 11, 2009

I'd replace it, if it were me.

trinogt · Apr 11, 2009

Guess what? The store actually had one in stock, but only when I gave them the part number! lol

I tested it cold, and it reads 27,000 ohms, the proper resistance for the temp it is at (72 degrees in the store lol)
Mine was 3000 ohms, way off! So I believe this to be the bad part. waiting now for the engine to cool so I can swap it out. Of course, I will report my findings. Thanks to all for your help! This site is great, and I will be staying! Glad you accept me with my Mazda... It was the closest I could find to a Ranger in my area, for the price. I am a true Ford man. I own two '70's trucks, a Tempo, a Merc Cougar, a '95 Thunderbird 4.6, and this truck, which I know is basically a Ford anyway lol. I also owned for 14 years a 1971 Torino GT, hideaway headlights, buckets, console shift, 351C 4V (M code) C6. Had to sell when moved to FL.

trinogt · Apr 11, 2009

Ok, think things are on the right track. After replacing the sensor, does the PCM take some time to adjust to the new sensor? I still got some pinging on my way to the video store, but on the way home, it seemed to be gone... Should I clear codes (not thta there were any) or disconnect the battery for a while, just to rest everything?

The temp gauge didn't go up at all. In fact, I could see it go down as I turn the key on! lol Do these clusters have an instrument cluster voltage regulator (ICVR), like the older vehicles? The temperature goes up normally when I use the scan tool to read it, so I guess it is the gauge at fault there.
The good news is, I found no fast idle on this trip. Engine rpm dropped normally when stepping on the clutch. Maybe time will tell if the problem is solved?

locovaca · Apr 11, 2009

The temperature gauge doesn't go by the ECT the PCM does, it goes by a different sender which is in the block. That part is much cheaper, around $8. I replaced mine a month ago, gotta pretty much drain the entire system unless you like drinking antifreeze

trinogt · Apr 11, 2009

Are you talking about the temperature sending unit? I just replaced that a couple weeks ago, and it was located in the thermostat housing, right next to the ECT sensor... They have slightly different harness connectors.
The reason I suspect a bad gauge is because even with the new temp sender, the gauge doesn't always work. Mind you, I haven't ruled out a faulty connector or open in the wiring... But it does consistently read correct temps on my scan tool, like I said.
I changed that when I replaced the thermostat, and was going to change the ECT sensor at the same time, when the store told me they did not have it, nor could they get it. Obviously, they were looking for the wrong part. lol
I do not have very good heat in the truck for some reason, which led to the thermostat change. The new 'stat is a little different than the old one, and only one part number shows for it, even checking other online sources. Anyone find their thermostat different? How do you like putting it in, sitting in a vertical position? lol

dmassey · Apr 11, 2009

trinogt said:
Ok, think things are on the right track. After replacing the sensor, does the PCM take some time to adjust to the new sensor? I still got some pinging on my way to the video store, but on the way home, it seemed to be gone... Should I clear codes (not thta there were any) or disconnect the battery for a while, just to rest everything?

The temp gauge didn't go up at all. In fact, I could see it go down as I turn the key on! lol Do these clusters have an instrument cluster voltage regulator (ICVR), like the older vehicles? The temperature goes up normally when I use the scan tool to read it, so I guess it is the gauge at fault there.
The good news is, I found no fast idle on this trip. Engine rpm dropped normally when stepping on the clutch. Maybe time will tell if the problem is solved?

Glad the temperature sensor replacement worked. You may have also noticed a drop in MPG's too since the PCM may have been keeping the engine in an over-rich situation a lot of the time.
Regarding the temperature sensor and the temperature gauge - two totally different items that sends information two different ways. The temperature sensor sends info to the PCM and the temperature gauge sends info to the driver - LOL.
Glad things are back on track.
Danny

trinogt · Apr 12, 2009

Actually, the truck felt like it was running lean... It seems much more smooth at idle and at speed now, for sure. There was no surging today, driving to and from church, even with the a/c on. That was refreshing!

Happy Easter, everyone!

trinogt · Apr 21, 2009

Well, I am still getting ping, even with midgrade fuel (89 octane).
Also, no temp gauge at all for a long time now, even with new sending unit. Anyone know the hot/cold resistance for the sending unit? It is new, but I would still like to test it. I really don't want to install another gauge in the truck... I am thinking if it is working right, must be the gauge itself, or the wiring. Want to dig into it. I don't like driving with at least some indication of temperature.

Ping, surging, revving?

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