Borrow a VOM then check the TPS per manual. I would also verify the wiring from the TPS to the ECU and check fuel pressure.
Dave
Car: KE70
Engine: 4age blacktop 20V, bought as a complete runner from an importer
ECU: Standard (Auto)
Ignition: SQ Engineering Distributor relocation kit
Fuel pump: Lift pump, surge tank, Bosch EFI pump, new lines and filter
Problem: Engine starts and idles fine but bogs badly when the throttle is applied. Will rev OK if throttle is applied slowly.
Already checked: Cam timing OK, ignition timing OK (10 degrees BTDC), no fault codes on ECU. Pulled plug off TPS and the idle jumped up slightly but otherwise not much difference. Pulled plug off MAP sensor and engine wanted to die. After doing this I got fault codes for both sensors, as expected.
Any suggestions?
Borrow a VOM then check the TPS per manual. I would also verify the wiring from the TPS to the ECU and check fuel pressure.
Dave
I had a similar issue. Faulty / incorrect knock sensor installed. Swapped it for a new one and the bogging dissapeared. Another thing that can cause hesitation is the VVT pulley.
There are a number of things as the guys have said. I have experienced the knock sensor myself on a couple of occasions. Leaky capacitors in the ecu is another common one.
Have you given the car a chance to warm up? My daily has a faulty temp sensor which causes it to big down until I've driven about a km. It's worse in winter than summer.
02 sensor or missing sta signal from the ecu won't cause it. Speed sensor input missing from the ecu also retards the timing a lil and will drop the rev limit but won't cause it to bog down.
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Make sure that there isn't any vacuum leaks, spraying soe engine start spray around the throttles would help determine that. If the revs go up then it's sucking it in somewhere.
The MAP and TPS sensors can both cause these issues. The TPS sensors however are much more known to wear out and need replacing. But make sure that the MAP sensor rubber line doesn't have any cracks or similar.
I have TPS sensors in stock but no knock sensors, but by memory I added some to my last order and they should be here in about a week. I should also start to stock MAP sensors seeing this isn't the first time that someone may of needed one.
My website: SQ Engineering - 4AGE and 3SGE upgrade/replacement parts
- SQ Engineering on facebook -
Please e-mail to contact me instead of sending a private message on here.
Could also be clogged injectors not opening which would explain idle and rev slowly. Typical problem if the engine has been sitting around for a long time...just have to check bit by bit until you find it...
I had a Silvertop do the same kind of thing to me.
Does the Blacktop have same Idle Speed Control Valve as Silvertop?
If yes, might want to check out how ISCV is plumbed.
I deleted mine altogether which made the symptoms disappear, opened up the top end and wide open throttle.
I had aftermarket ECU so I could tinker with the idle to get it right, not sure how Stock ECU would react.
Good luck with it and let us know how you get on with this issue.
It will throw a check engine light if it is unplugged , I had a high idle issue years ago which turned out to be a stuck valve.
Carby cleaner usually un-sticks these.
Ae86 Drivingclub - Toyota AE86 Car Club where AE86 | KE70 | Toyota 86 / GT86 | Subaru BRZ | Scion FRS owners
Finally got around to looking at the car again today:
TPS resistance is in spec and wiring to ECU is all intact
Sprayed ether all around intake and no obvious vacuum leaks. All vacuum lines are new.
Knock sensor is connected but have no way of testing it.
Pulled ECU apart and all looks fine (no leaky capacitors)
Unable to check fuel pressure as I don't have a gauge but both fuel pumps and lines are brand new, wired and plumbed correctly. FPR is factory and untouched. What would be potential causes of fuel pressure issues?
Car idles really high with ISCV disconnected, much better with it on.
When I was messing around with the dizzy it definitely seemed more responsive when the timing was advanced.
Also noticed there is a lot of carbon buildup in the intake manifold behind the throttle plate. Car has backfired out the intake on previous starts. Is this anything to be worried about?
Check the condition of the dizzy cap, the carbon pile can wear out over time.
Ae86 Drivingclub - Toyota AE86 Car Club where AE86 | KE70 | Toyota 86 / GT86 | Subaru BRZ | Scion FRS owners