I rebuilt my ca18det recently and I can't find out why it misfires at just over 4k, the revs actually come down slightly even though my foot hasn't moved and then if you apply more throttle it will go past 4k and clear up and go to the limiter no problem. it's got a standard ecu no chip or anything a lightened flywheel, large fmic,adjustable fpr set to 38psi at idle with the vacuum pipe on the turbo is the standard t25 but with a t28 turbine machined to fit and it's running at 8psi and a 3" exhaust if anyone has any suggestions as to what might be the problem it would be greatly appreciated there is a video of the problem as well https://m.youtube.com/watch?v=rCdRMCOR7UU also I haven't actually driven the car since the rebuild due to the rest of the car being in bits, will it be better when driving?
Just In case the original fpr was faulty, it made no difference anyway I'm guessing I will be better off sticking the original one back on then?
Yea it's generally best to keep the stock FPR, it just works (failures are quite rare). I take it you have a walbro fuel pump on there as well?
Yeah walbro 255 I replaced the original lines with stainless braided ones as well just because the original ones were real crusty also it tends to Pop/bang a lot even at low rpm when revved and I'm pretty sure the alternator is not charging the battery will this have anything to do with the issues im having?
Yea possibly, although it sounds like abit of a mess. You might want to start with the basics, give it a good service with the correct parts, check spark plug gap, check the timing, check the cam timing, pull any ECU fault codes etc etc etc.
Ok so I've done a few things... Changed the plugs with bcpr7es-11 the originals were light grey ish (now bearing in mind the car has only been idled and revved but not actually driven is this a good colour?) Removed upper and lower timing covers to check I hadn't put the cambelt on wrong but everything lined up etc etc, I put it back together and set cas to 15 with a strobe light etc. Did a compression test, 155-160 psi on all 4 Changed air flow meter Did the ecu fault code thing and got code 34 which is apparently the knock sensor being bad what issues will this cause? Changed a vacuum line that was cracked All of this has resulted in little to no difference Other things I've noticed is I can hold it at the rpm it misfires at which is around 4.2k and the tach needle moves erratically back and forth (even though the engines rpm does not change) it's a bit like it has a bee r limiter fitted so is there some kind of electrical interference somewhere? And if you're very gentle and increase the Rpms slowly it will actually bounce back like its being limited but then if you stamp on it the misfire is invisible. Also it stumbles and pops/crackles/bangs under 3k rpm when revved but sounds smoother above 2500 -3000 rpm, it's also very hesitant about revving once fully warmed up if the throttle is opened fully very quickly, and it sounds like a lot of air is rushing in somewhere before it actually revs even though there are no leaks, is this noise normal? it's much better when cold It idles fine either hot or cold with the odd pop here and there from the exhaust it also takes a bit more cranking to start when hot sorry for the long post I'm just trying to give as much info as possible I'm also starting to think my car hates me haha
Sound's a bit like the RB stage one tune / coilpack problem, But then again If it's like a R body that will probably pull the timing back
If the tacho is jumping without the engine RPM changing it could be a crank angle sensor / wiring issue.
BCPR7ES-11 plugs have far too large a gap, you need to regap them all to 0.8mm. If you're getting a knock sensor fault then check the wiring and/or replace the sensor, no point trying to troubleshoot when you have a known fault staring you in the face.
I will check the wiring and voltages going to the cas and if all is good I'm guessing I will be needing a new crank angle sensor then?
Thanks for all the replys I will regap the plugs and try to sort the knock sensor issue this weekend and yeah I did both, the marks lined up and I counted the teeth at least twice I was hoping it would be out a tooth or two
Pop the CAS out and check the spines on the CAS and on the cam, you could also double check with the strobe. When the cas/cam splines wear out it can jump a tooth out on the cas knocking your ignition timing way out.
Make sure you haven't got the idle control valve plug and the closest injector plug the wrong way around. Been there done that.
Ok so I've checked wiring to injectors etc and all is the right way round, the plugs have been re gapped to 0.8 and the knock sensor wire was hanging out the back of the plug so I've repaired that, reset the ecu ran the car again for a bit checked the code again and I've now got code 55 so all is good. There's a definite improvement under 3000rpm it sounds much smoother and doesn't stumble like it did before. it revs ok to 7k until the temperature gauge gets to half way and as soon as it does it won't rev smoothly at all it hesitates massively I've made a quick vid to show the way it revs when warmed up And I've changed the temp sensor already so it can't be that, and can anyone tell me what the screw on the afm does? I have two and they've both been messed with by someone else
AFM screw sets up idle CO2 mix, you need a gas analyser to get it correct. The AFM with the screw is pre-facelift, to run that you need a pre-facelift ECU and no lambda sensor. If you mix and match you can get issues.
Where is the vac line for that dump valve going? What is the setup with the vac lines for the FPR at the back of the head? Do you still have the hot start solenoid connected?
{} The car is a 1989 pre facelift with a preface lift ecu and there is no lambda sensor The hot start solenoid has been ditched, I've just run the vacuum hose that comes out the back of the inlet manifold to the fpr and the vacuum hose for the dump valve goes to the port on the side of the inlet manifold just behind the throttle body. I've also got a innovate lc2 wideband controller with the gauge that I will fit at some point so I can see what the afr's are doing
