Maf reading too high
#1
02-01-2018, 12:02 PM
Maf reading too high
2005 rodeo 3.0td auto. Engine management light on, not revving over 3k. Local garage checked everything from fuel pump, turbo, boost pressures, air filter, injectors, cat, egr valve... Then an identical truck showed up which had a blocked cat. Once that was sorted he took all the readings off it (ours already had multiple errors so earlier diagnostics were fruitless). He then compared those readings to our truck. Everything was the same assist from the mass air flow and desired mass air flow.
Mass air flow was reading over 1600 compared to 520, and desired flow was over 600 compared to 400 something. He then took the air flow meter off the good truck and put it on ours. Hey presto the truck worked perfectly. So he ordered a new air flow meter, put it on ours, the truck wouldn't work again! So he tried the flow meter off the good truck again and it made no difference! Anyway he'd had enough and said it wasn't worth putting more hours on it, so we brought it back.
We cleaned all the contacts on the plugs we could find (fuel pump, throttle body etc), checked the condition of the wires from the air flow meter all the way to the ECU, they looked fine. Turned the truck on. It revved fine, took it for a drive, it drove perfect. We thought we'd sorted it. Put the shielding back on the wires. Truck stopped working again.
So we thought it must be a dodgy connection/write somewhere. While we were looking again we took the wiring loom out from in front of the radiator, the revs picked up, and it revved fine again. We then checked every wire there. While we were fiddling round the engine was ticking over. Every now and then the revs would pick up slightly, and that would indicate that the engine would rev fine again. We thought we had traced it to the 5 wires from the maf meter. So we installed new wires bypassing this section. No joy. This morning we were fiddling with the plug into the maf meter and the revs started varying again, but it wouldn't rev over 3k. So we thought the plug might be faulty. So we bypassed the plug and wired straight onto the pins on the maf. No joy.
We're pretty stuck. Is there anything that could cause the maf to read incorrectly intermittently? Any suggestions?
Mass air flow was reading over 1600 compared to 520, and desired flow was over 600 compared to 400 something. He then took the air flow meter off the good truck and put it on ours. Hey presto the truck worked perfectly. So he ordered a new air flow meter, put it on ours, the truck wouldn't work again! So he tried the flow meter off the good truck again and it made no difference! Anyway he'd had enough and said it wasn't worth putting more hours on it, so we brought it back.
We cleaned all the contacts on the plugs we could find (fuel pump, throttle body etc), checked the condition of the wires from the air flow meter all the way to the ECU, they looked fine. Turned the truck on. It revved fine, took it for a drive, it drove perfect. We thought we'd sorted it. Put the shielding back on the wires. Truck stopped working again.
So we thought it must be a dodgy connection/write somewhere. While we were looking again we took the wiring loom out from in front of the radiator, the revs picked up, and it revved fine again. We then checked every wire there. While we were fiddling round the engine was ticking over. Every now and then the revs would pick up slightly, and that would indicate that the engine would rev fine again. We thought we had traced it to the 5 wires from the maf meter. So we installed new wires bypassing this section. No joy. This morning we were fiddling with the plug into the maf meter and the revs started varying again, but it wouldn't rev over 3k. So we thought the plug might be faulty. So we bypassed the plug and wired straight onto the pins on the maf. No joy.
We're pretty stuck. Is there anything that could cause the maf to read incorrectly intermittently? Any suggestions?
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