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I will check the anchor bolts to the rack tomorrow morning, would be great if that’s all it is. It partly sounds like it’s coming from the strut top mount, the strut was shot on the particular side I tested from, had 1 wheel up off the ground and one on the ground. Found it strange it was harder to make it clunk once preload was increased. Installed a new UJ months back thinking that was the source of the noise. Its been this way for months but now it’s getting concerning. Could get out the mechanics stethescope and listen I guess?
I also have the 1.8 VVTI in my mr2 roadster, 165psi is okay. For reference my engine is at 65k and has 180psi compression. Your piston rings are worn but not bad. When the engine was new it will have had around 225psi compression.
What makes you think it’s the cats? Surely the 20% positive fuel trim is what’s causing a rich reading from the downstream sensor. Could try a different o2 sensor in place of one of the upstream ones and see if the readings change. I had this problem when one of my o2’s got damaged and would only put out low voltage. I would say swap them round if both banks read different trims but it seems that’s not the case. Do your trims return to 0 under load or do they stay positive?
I’m not familiar with your vehicle. Although i’d agree your cat is showing a rich reading. Probably from the positive trims. Would definitely start checking for that 5 volt reference. ScannerDanner has a channel on youtube full of diagnostic information regarding lean conditions. Pour some water on the engine in different places and listen for a stumble, just to double check there’s no vacuum leaks. Or perhaps have it smoke tested by the mechanic. You need to have the key in the on position without the engine running in order to get the signal from the TPS connector.
An easier way with the multi-meter would actually be to put the ground lead on your multi meter to battery negative then use the positive to probe the connector for 5 volt reference.
To test for exhaust restriction you can use an exhaust backpressure guage. It appears your engine’s running quite rich at .7 and .8 volts. Throttle position sensor values from car to car. It appears maybe there’s a wiring fault somewhere. Keep an eye and see if that code comes back. I would try resetting your cars ecu now you’ve changed some parts plus it’ll reset your fuel trims. Seems like the TPS is putting out the wrong voltage and affecting your trims as a consequence. Do you have a multimeter? Perhaps you could run a continuity test by backprobing the connector and the associated pins on the ecu plug. Running so rich won’t be helping the engine to keep running either, another thing you can do just to rule out vacuum leaks is pour water over your vacuum lines, if there’s a leak the engine will stumble. Focus on the TPS for now as that’s very likely causing your issues. Hope this helped
I’ll try unplugging the post cat sensor and see what it does, the oscilloscope is definitely on my list of tools. Thankyou for your help also, wiring looms seem like a nightmare of a fault when they go wrong!
Also leaking fuel injectors can contaminate your oil with petrol. So i’d be checking the oil for a fuel smell.
Have you checked your fuel pressure regulator? Also your oil level. I’ve just had this problem and oil being sucked up the PCV hose was causing rich trims. On some cars it’s connected with a vacuum line. It should be dry to the touch, sometimes the diaphragms rupture and fuel ends up being sucked into the vacuum line.
So from what I’ve read about the DOD system it shuts cylinders down automatically and will switch to v8 mode after 10 minutes. What do the other DOD cylinders show for running compression? Just to determine if this is normal behaviour for the engine. If it’s the same then your issue likely isn’t a mechanical one. Another thought, you could try swapping fuel injectors with another cylinder. It may be those DOD cylinders don’t actually have compression when they’re deactivated.
So I ran an exhaust back pressure test and found no restrictions. However I did resolve the fault eventually. It turns out the previous fuel injectors had contaminated the oil with fuel and pushed it well over the fill line. New oil and filter and the negative trims are gone. However the engines now running a tad lean. Am gonna chuck some water over it and find the leak, it appears my smoke tester isn’t gonna find it. I can’t believe I’d overlooked something like this.
Could an exhaust blockage cause rich trims by some chance? The manifold has 2 precats in it. I was going to do an exhaust back pressure test tomorrow.
The chip in the airbox housing, I meant a piece is chipped off. I tried running it today without the filter or any obstructions and it made 0 difference to my trims. Have ordered an endoscope to check inside the manifold. I’ve read that the divider can sometimes collapse inside these plastic manifolds. A camera seems a sensible idea to check where I can’t see. Air temp sensor is built into the MAF on this vehicle. And thats what I was questioning, is the MAF actually over reporting. Perhaps pick one up from the scrapyard for cheap and check it with that. Whats throwing me off is the way both banks are affected differently. The MAF seemed to be reporting a higher reading after cleaning. Contact cleaner is electronic safe, it’s for cleaning corroded contacts up. Although I also discovered it appears to be MAF safe. I do have an offbrand MAF installed and no longer have the original one. Have to see if I find anything with the endoscope, although im skeptical, manifold blockage is something I’ve overlooked. I’ll take notes before and after a different MAF
