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Toyota 4age black top, who is the diagnostic expert?


Seedy Al

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Hey chaps. So basically, my partners sisters car has an issue or two, and thought I might try for some advice from some people that might have fucked around with black top 4ages more than me.

The vehicle, ae101 bz tourer with a black top clearly. 1997 vintage.

The issue or issues as such, as they maybe related. Basically it is hesitant during low revs up to around 4000rpm then most often clears put and goes very well as a 4age should. Cruising seems fine, and seems pretty good at wide open throttle. So is most noticeable at quarter to half throttle sort of thing. Also, every so often while cruising along at 80ish, so I gues around 3000 rpm, it hasca blatant miss, but only for a second.

What I have done so far is new plugs, as old ones were super ashed up, so yes being a black top it uses some oil, but not fuming blue smoke all over the place bad at all.

Also replaced the rotor and the cap had previously been replaced by me on request from someone else as to this being the cause, which is wasn't. However since doing the rotor and plugs it does seem ba bit better as it was lot more missy before. The leads I have swapped with some known to be good second hand ones. However not the coil lead, which could be an issue but I would be surprised.

I have also cleaned out the filter for the sensor, and tried the ecu for codes. There were none.

Scan tool on live data is showing that the coolant temp sensor is working like a boss.

So, where to from here? I have read a bunch of threads. Every one stating its a common problem but never really getting down to how to fix the cunt. One suggestion was tps, so I am going to check and set that along with the base timing tomorrow. Another was that the oxy sensor could be toast from oil contamination. I guess I could commit to buying an oxy sensor, but. If people have some first hand experience with these rad as shit little motors and how to address this silly issue I would love to hear about it.

Thanks dudes.

Seedy mother fucking al

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Sounds super similar to what my old daily used to do occasionally (without the miss though), I did a bit of research and concluded it was the o2 sensor. Ended up selling it before I got chance to replace it though but that'd be the first thing I'd check out.

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Mine had the crappy running at low throttle and occasional miss at cruising speed.

 

I ran it on 98, replaced leads/plugs/dizzy cap/rotor, did a trackday at taupo, replaced the o2 sensor, advanced the timing, fiddled with the tps, hit rev limiter everyday and it still ran the same.

 

I was going to try a new coil next but sold it instead.

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My black-top also does similar, or-though doesn't sound quite as bad (ours has had motor re build also). It's just not so good at low rev range, our old silver-top car just seemed to be allot smoother. 

 

I was going to look at: smaller zorst system, clean throttle body, dizzy cap n rotor, plugs and check the sensor flexi tubes and the likes.   

 

No real help sorry. 

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02 sensor is more for emissions than 'general running' of the car. Black top is map sensor right? Check the vacuum lines etc. Is it using more fuel than usual? Give the coolant temp sensor a trst/try (it's cheaper than a 02 sensor).

One day I will need to do a write up on efi

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Sorry my wall of text might have been a bit much

Coolant temp sensor seems fine, based on live data

 

Seems worst when cold, maybe, but still present through all temp range.

 

And I have checked the vac line to the Map when I Checked the filter that feeds to it.

All Seems good and cleaned it yesterday

 

If I had the smoke machine here at the moment I would give it burn and check for intake leaks, but at this point I dont Lol

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Yeh, deff should be running on 95+, they are 11:1 comp ratio I think.

 

If she drives like a blouse, it may just need a good nang, they sometimes carbon up due to being driven too nicely, and a good thrash clears them out. Well I had a silver top that would slowly die due to this, a good nanging always cleared it out.

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