11 replies to this topic

[brivinci]

I've discussed this before a few times but finally made a video to demostrate a couple of the issues my car is STILL having. 

 

(search 1RfiNv8VTrQ on youtube if link does not work)

 

This was done on a well warmed motor. If I burry my foot into the pile at idle, the car misses and sputters until it gathers itself and revs. On the reverse, the idle falls to 1000-1200 for a second or two before settling to 850 or the likes. This has been an issue I have notice for some time. I just put the car back on the road after rebuilding the head and cooling system due to a burst rad hose and an overheat issue. Motor is VERY healthy. Great oil pressure, good consistant compression, water temp never fluctuates. Unit recently, it pulled brilliantly as well. Today is the first day I have driven it since the head/coolant work and there is a hesitation happening, especially noticeable in 4th. Has a hard time pulling in the lower rev range and I can sometimes feel like the car is held back/bogging at times. If I blast through the gears to redline, 1-3 feel great but 4th gives at stutter/boggy feeling around 4-5...but that at a pretty high speed so I haven't had too many times to retest.

 

One thing I have felt for a bit is that the car is VERY touchy in first at low RPMs. On and off the throttle in, say a parking lot, the car can buck a bit if not very careful

 

Being in the states, i do not have easy acces to a scanner but all previous times I have plugged it in, everything has checked out. All my vac lines have been replaced with proper silicone units. Heated intake unit has been removed complete, plugged and MPi air intake arm fitted to stock SPi airbox. New fuel trap just to be safe. I did remove the Pressure temperature compensator and noticed its trashed. Sounds like there are magic beans inside of it. I reinstalled and will just leave as is. Exhaust is newish and has been de-catted. Replaced the Lambda a bit ago but have not tested lately. I recently sprayed starting fluid around throttle body to see if there are any strange leaks and nothing came of it.

 

Just trying to give any info that might help...even if a bit long winded. Any thoughts?

Edited by brivinci, 08 August 2017 - 08:45 PM.

[tmsmini]

What years had the throttle pedal switch? I think it was earlier than your car, but I am not completely up on the SPi.

Terry

[brivinci]

That was earlier cars. Maybe only first year SPi cars. Mines does not.

Just for the record, the fuel filter is new. As are the plugs. Cap and rotor have been replaced a few years back and were inspected and cleaned. Wires are the upgraded 8mm type. Coil is original. Harness has not been hacked about in any way.

[genpop]

Buy interface and download mems-rosco, so you will be able to log all values of running engine.With mems-analyser you may compare logged values and you may reset ecu. All by about 20 bucks.

[FlyingScot]

What years had the throttle pedal switch? I think it was earlier than your car, but I am not completely up on the SPi.
Terry

First ones up to 1993

FS

[FlyingScot]

Check throttle position sensor either unplug and check with ohms range on multimeter or backprobe the connector when on. Middle and outer your looking for a smooth transition. It's a potentiometer and the track can wear leaking to spurious voltage changes through the range.

FS

[brivinci]

I've been thinking TPS as well and need to check it.

Genpop, can you give me more info on the mems-rosco? Is it a unit you can buy or build? Never heard of it

[genpop]

hi brivinci,

have a look to the thread "spi code reader"

[Midas Mk1]

Do SPi's have an iacv? Caused me all sorts of issues with idle with my MPi, not ideal having a 4.5k idle in busy traffic..

 

If an SPi is like an MPi in TPS respect, you'll need a sykes code reader to set the tps stop. 

[cian]

I've a code reader if your a Northern Ireland resident your welcome up to my shop for an inspection

[FlyingScot]

Do SPi's have an iacv? Caused me all sorts of issues with idle with my MPi, not ideal having a 4.5k idle in busy traffic..
 
If an SPi is like an MPi in TPS respect, you'll need a sykes code reader to set the tps stop.

Nope they have a stepper motor which opens the throttle , but they do have a throttle stop which should not be moved which sets the reference position of the stepper motor (it doesn't have a feedback).

FS

[brivinci]

The idle really isnt the main issue. That stab the throttle/stumble issue annoys me to no end but the strange hesitation/stumble/bog while on the move is the main things here.

 

Wil give that thread a look. Thanks.