1GGTE Woes

[Big rob]

In February my timing belt let go which I replaced and reset all the valve lash. After getting the car back on the road it hasn't driven the same.

Here is a list of issues:

1. Cranking isn't as crisp as it used to be, there is noticeable longer cranking period.

2. Fuel consumption has increase from 10L/100km to 12/13L/100km.

3. When driving the car cold is very odd:

eg. Take the throttle to ~20%, the car slowly accelerates and holds a steady speed whilst the turbo chargers audibly continue to increase speed. From here there is a considerable hole where increasing throttle percentages do cause the car to accelerate and gain speed. More throttle fed in there is a kick where the car accelerates, if the engine is revved out with full load there is a situation around 5000rpm - 7800rpm that feels like lots of timing is pulled and re advanced over and over which creates a VERY jerky ride.

There are no codes, the engine light hasn't illuminated.

The plugs are fine, I re-gapped them slightly tighter around 0.65mm to see if that would combat any of the issues.

All cylinders are within 5psi of compression, the gauge was reading 185psi - 190psi which seems very high on a 8.5 - 1 compression ratio, but they are even.

Timing at idle is 10deg BTDC.

The reluctor gaps in the distributor have been reset to the 0.2 - 0.4mm tolerance.

The car drives pretty well as it used to once warmed up my butt dyno believes it makes similar power. There is just a clear night and day difference between cold and warm and it uses more fuel.

Any ideas are very appreciated,

Rob

[CLG]

You get rep for supporting your question with supporting info - I wish more people would take note and follow your example!

As for your issues:

1: Try a different battery - you've had the vehicle off the road for approximately 2 months, which may be long wenough for an old battery to drain and alter the internal matrix (especially if it went flat over that time). If the "newer" replacement battery cranks faster/better, I'd say you'll be up for a new battery shortly. If the cranking speed remains the same, including the duration till it kicks into life, I'd look at your injectors and fuel pressure - I've had injectors that have sat for period of time start leaking - they lose pressure behind the injector, and it took a couple of cranking revs to regain the pressure for the injectors to fire adequately.

2: Assuming you're driving in the same style and locations, and that you don't have any error codes as mentioned, maybe it time to look at the mixtures coming out of the tailpipe. Check your idle adjustments on the AFM, ISCV, and oxygen sensor - they may not be throwing an error but double check them all. also consider it may be time to service the injectors - this would account for issues in your cranking too. If they haven't been done recently, it's worth spending the money to have them cleaned properly and the filters replaced, along with a flow test - it will eliminate possible causes too once done, and confirmed as servicable, and it doesn't cost that much to do.

3: Check TB for build up of carbon, oil, ..., check vacuum lines, check air lines, go mad with the soapy water to check for vacuum leaks, and check the sensors and lines to them. Check coolant lines to the to and from the TB for flow.

Clint

[auto351]

The cam timing will also effect the compression reading, could be the timing belt was installed incorrectly or just different to how it was before.

EDIT:
Another thing, the harmonic balancer may have moved shifting the timing reference

[Big rob]

Thanks guys,

The car sat for approximately 1 month and the battery is maybe a year old but I'll swap in another one and see if there is a difference.

l'll go through the AFM, ISCV and oxygen sensor and have the injectors cleaned/flowed, next on my list was to clean the ISCV. The car only has 98000km on it but 20 years does like to degrade rubber i.e the timing belt.

I have actually had the car not start from crap building up in the TB so I'll pull the hard pipes off again and have a look.

Auto351: I am sure the cam timing is in the correct spot, initially I thought this was the culprit after driving the car a little but the cams are spot on. Before installing the timing belt I made sure the harmonic balancer had not shifted and 0BTDC was infact 0BTDC.

Thanks again,

Rob