214jay

Hi I am having some problems with my 350TPI.


When I lightly rev the car to around 2000rpm the engine shakes and backfires (through exhaust) and sounds like it is missing. When driving as soon as it hits the around 1500rpm it missed badly and backfires continuously, it’s a real struggle to get it up to any speed. For some reason when the EST circuit is disconnected it runs perfectly without hesitation or backfiring.


Prior to this fault, the engine and engine bay was in bad shape (rusty) but running okay. I took the engine out around 1.5 years ago to clean everything. I stripped the heads off the engine and replaced the head gaskets and all of the upper plenum gaskets etc. Replaced all of the ignition components, new CTS, new TPS. Deleted aircon, deleted AIR (already partially disconnected) – Cats removed by previous owner. New exhaust manifolds, new fuel filter, new vacuum pipes, checked for vacuum leaks everywhere using starter fluid, no exhaust leaks. Fuel pressure at injector rail steady at 47PSI. Have added new extra earth straps to both heads and reads nearly 0 ohms across the engine to ground. Base timing is set at 6* and all plugs are in correct places on diz. New fuel and fuel injector treatment. Injectors ohm out okay.



The only thing I have noticed which I cannot explain is the new rotor became quite burnt after a short drive (see pic below), tried a new rotor, Cap and leads but no difference to fault.


Has anyone got any ideas? Its driving me mad and I don’t want to keep throwing parts at it in the hope it may cure the fault as shipping from USA is killing me!



Thanks in advance!!


Jay

sofakingdom

iTrader: (1)

Looks to me like the rotor is pointing at the wrong terminal of the cap.

Try moving all the plug wires one place clockwise and advancing the timing a little bit from wherever it is, until it runs the best it can. Don't worry about the "number"; after moving the wires, worry ONLY about whether you are making it run WORSE than it would if it was set somewhere else. Then set it to where it runs THE BEST, regardless of the "number".

214jay

Thanks, I will give that a go today. Would it even run with the plug wires that far out? Had a 40mile journey in it yesterday with the EST unplugged and it ran spot on.

Have noticed with the EST plugged in the engine also makes an irregular pinging/tapping noise but cannot work out where from. Goes away with EST unplugged.

214jay

I tried moving the plug leads as suggested above but the engine won't run. Have put plugs back and back to the same problem. Any ideas anyone?

TallTim

iTrader: (2)

I would get up to 2500 RPM and same thing. Backfiring though exh and intake, shaking etc. Found I had too much base timing even tho I set it it got off somehow again. Check base again with ESC wire off, also could your timing mark be off? There is a recent thread here about pulling #1 plug and TDC and such.

214jay

Yes I have checked base timing a number of times. Have tried it between 0* and 10* with no change. Currently set at 6* with no.1 cylinder at TDC. Harmonic balancer is solid also with no play so that shouldn't be off.

214jay

Any other ideas? It wouldn't be to do with valve lash would it? All the components are stock and set at 1/4 turn past 0 lash.

greasegrenade

any fault codes? I would rotate the engine by hand clockwise to line up timing marks at balancer.Then pull the distributor cap and look if the rotor is pointing at number 1 terminal in the cap.If its pointing way off rotate it again clockwise and line timing marks up again.Then If the rotor is not pointing at number 1 terminal adjust the distributor/timing.Also dont forget to unplug the little brown wire while adjusting timing.For troubleshooting would use factory timing specs.

greasegrenade

lash can cause problems but you need to fix known problems first...burnt rotor button

sofakingdom

iTrader: (1)

Move them one notch the other way and try again.

214jay

No fault codes. Rotor is spot on and pointing to no.1 terminal when balancer is lined up. As above, car runs flawless with the Brown EST unplugged, set at 6* before 0. Plug EST back in (after disconnecting battery to clear code) and runs rough again. Timing has been set a number of times using the correct procedures.

Have tried moving both clockwise and anti-clockwise and the car just splutters and won't stay running. Returned plugs to initial place and fires up and turns over fine, until driven or revved to 1500rpm.

I have installed a new rotor and drove around 50 miles with EST unplugged and no signs of burning so far.

greasegrenade

Original balancer and timing pointer from tpi motor ? External esc module? New timing chain ?

greasegrenade

the burnt rotor looks like a rotor phasing problem.Is 6 degrees before top dead center oem timing?

214jay

Yes original balancer and timing pointer. I checked these when engine was removed and the balancer was still solid. Yes external ESC module on the drivers side firewall. As far as I know the timing chain is the original (car has 60000 miles [96500km] on the clock).

Yes the 6 degrees before TDC is what is listed under the hood and in the manual.

greasegrenade

got access to another esc module for testing purposes?

214jay

No unfortunately not, they are few and far between where I am based. It was working fine before I had the engine out, is there a way to test it?

greasegrenade

Oh sorry I see..try unpluging the knock sensor.Leave the brown wire(timing connector ) connected.Start engine.

214jay

Sorry for the delayed reply, it had got too late to start the car yesterday. So pulled the knock sensor, fired it up with EST connected and no change at all. Car runs perfectly at idle, rev to 1500rpm and it shakes, hesitates and backfires. No fault codes either. Plugged knock sensor back in and still the same.

214jay

Slight update. Just redone timing again and still the same fault. However I thought I would try revving the car to 1500rpm (where it faults) and try the timing light on each plug lead. Flashing increases with engine Rpm on plugs 4, 6 & 8, however on the remaining plugs the flash has large gaps where there is clearly limited spark...Any ideas??

214jay

Another update. Unplugged the 5 pin lead from the ESC module and started the car. The timing is more erratic and jumps around (though this does not happen with the EST bypass wire disconnected?!?) but the car runs slightly better, still hesitates at 1500rpm but not backfiring as much.

214jay

Any ideas what could be causing intermittent spark when revved? Could this be the EST module?

tyeo098

Timing chain jump a notch?
You can set the harmonica balancer to 0 but really be 20* off.

214jay

Yes that could be a possibility (is this likely on an engine thats only done 60k miles). The only strange thing is that it drives perfectly without hesitation with the EST unplugged, if the timing chain was a tooth out I would expect it to also run poorly. What is the best way to check if the timing chain is out?

I have ordered a new EST module, knock sensor and a heated o2 sensor so will update if that helps at all.

214jay

SOLVED!!! Thought I would provide an update...The problem had been getting gradually worse and idles rough when cold and really bad revved to 1500rpm and won't go above.

Today I received a bulk order of parts and fitted the following:

Knock sensor (On removal the old one was quite corroded where it sat in the engine coolant);
New copper spark plugs (to eliminate the previous platinum new ones as a possible failure);
New EST Module;
Coolant Temp Sensor and Plug (in case the previous new one was faulty); and
New 3 pin Heated O2 sensor.

Anyway, not sure which it was in the end but it would appear the problem is solved and she is running brilliantly! Have not taken her out for a test drive yet but revving and sounding so much smoother so looks like problem solved! Thanks for all the help and suggestions.

214jay

Spoke to soon, was running lovely until I took it for a drive...lasted 30 seconds of PERFECT driving...then back to square one, can hardy drive it now and back to crappy revving. Giving up on this car, I am now out of ideas.