7afe no power

[bluea]

I have 98 avensis 1.8 7afe engine. It lost power and check engine light on. Will rev to 3000 but drop right back.  some misfire.so can only crawl in first if no real load. No codes on obd when pins crossed.check engine light gone out. various sensors seem ok. Any ideas appreciated.

[Konrad C]

Hi Colin, There are a few possibilities crank or timing sensor, failed leanburn sensor, MAF/MAP sensor, vacuum system controlling the variable inlet, bad connections to the various sensors mentioned. The Haynes manual does not cover much, but I managed to download some technical PDF's a few years back. 
Have you checked the spark plugs (Denso Iridium SK20R-P13 and nothing else) and when last has the cam-belt(and tensioner) been changed? Also look at getting genuine HT leads. The spark has to be strong and fires twice as much (wasted spark). The spark plugs run really hot, and only Iridium is up to the job. Anything less will melt!  

The car is 19 years old and the vacuum pipes may start to fail, depending on the conditions. 
Here is a weird one that happened to me, a few years back the leanburn cable got caught in the air-con fan. The heater cable of the sensor was damage and exposed. I did a repair and re-routed and secured the cable. At the time, the EML illuminated warning me of the problem. If the other cables had been damaged, the car would have run poorly. Check that the leanburn/O2 cable is secured between the fan cowlings away from the blades!
Check the vacuum switch to the inlet manifold is working properly and connected. See the following post:-

It is best to work on the simple basic items on the engine before going to the more expensive items (nothing is cheap these days).      

[bluea]

 

Konrad.  Really appreciate your detailed reply.  You mentioned the O2 cable, I had seen that very same thing with it being hit by fan blades when looking around before.didnt think any damage though. But checking again now I see the blue wire is exposed half way along! Also code 21 is now flashing, but that maybe from disconnecting plug while testing,and not clearing yet.  Seems a big suspect now though. Did you  resolder? I gather they are not brilliant at being redone?

? best source of replacement if not dealership.

Just saw your valve actuator post. This is very interesting, I heard a new noise to me and tracked it to that part, as ignition is turned on I noticed it move and make sucking noise. Is that right? never noticed it before. I rang Toyota they struggled to identify part,but helpful chap is getting back to me.    I'm not sure what you did there, will reread but perhaps you could clarify. Again big suspect.

Covering some other things you mention. Crank sensor replaced last year after no start when hot. Cambelt five years ago,I've not done the mileage,but time wise I guess it's due a change. I have Iridium plugs in there, again a few years old, but my mileage is really low so possibly not helping some issues. So usual problem find the right part and perhaps not to much expense or  say goodbye and move on. Thanks. C

[Konrad C]

Bluea. From what I remember I the wires was broken near the plug. I removed the sensor and from the car, then removed the plug and then crimped or solder (I cannot remember which), then got wrapped insulating tape and cable sheath to cover the cable. I then more insulating cable to wrap and protect all four cables and thick cable cover. Then replaced the plug. Then replaced the sensor.

Since only the heater cable (black) of the leanburn/O2 sensor was cut, only the EML illuminated (code 21). The fix cleared the EML, and I deleted the fault code by removing the EFI fuse. If the signal or earth cable are cut, then the ECU cannot run the engine properly. That may be the reason your car is running badly. 

When I replaced the sensor, the stiffer cabling made the routing slightly easier, so it stayed in place between the two fans. It was the air-con fan that cut into the leanburn cable.      

[bluea]

Konrad, thanks, I'll tidy up wire it's not sheared completely just exposed. I did remove negative Battery lead and reconnected, the code disappeared. The vacuum actuator troubles me, helpful chap from Toyota Brislington getting back to me tomorrow. C