Rb20det ignition timing issues!

[Drift24tsx]

Ok so.. I have a silver top rb20det in a 93 s13. My issue is timing is all over the place. I will set it at 15 snap throttle a few times raises then sits right back at 15. How it's supposed to.. however if I snap it just a little and real quick will sit at 5 can run at idle for 20 mins never moves. Give it a full rev and let go sits at 15. Snap it real quick again 5 snap again real quick 15.. again snap it 0.. then back to 15.. idle is good tps sits at .45 whether it's 15 30 0 5 etc..Electric fans come on drops to like .43 snap it back at 15.. soo... issue is something is changing timing and can't figure it out.. also if it's at 15 and I tighten the bottom and top left bolt on cas timing stays at 15 go to tighten top right jumps to 30.. so.. I leave the top right bolt loose and stays at 15 till you give little snaps of throttle thenot jumps around. Please help!! So much research I have done and can't find anyone that has timing jumping like that. Ty in advance!!

[Drift24tsx]

Bump! Please any help appreciated!!

[hanzbrady]

Hey man, so the timing will only stay exactly at 15* if you're in some kind of locked timing mode. If the engine doesn't have it's base timing locked it will move according to the ignition table and other given inputs.

[tb13]

If you are seeing 15* at idle with the engine warmed up and the car is running properly, there is no need to worry about the timing moving around.

[Drift24tsx]

That's the thing tho it doesn't run 100%.. when I originaly drove would fall on its face below 4k and at idle could here a misfire through exhaust every few sec or so. But when I hit boost it pulled hard! So I thought let's check timing. Checked at #1 both primary and secondary and both read 30 so borrowed a older light from a friend still said 30. So rotated to the right (retard) and got like 17 maxed out. Drove it was way worse even during boost.. so put to the middle of cas again and read 15 sweet ok was a fluke.. drove it same thing.. went to check it said 0.. snap throttle I noticed it changed to 15 if I barley hit throttle go's to 0 and again stays unless I hit throttle again.. if I try and snap quick and let it wind out it hesitateS and pops through intake. Sometimes when I snap it and watch with gun it will go way below 0 retard for a quick second then jump back to about 15-30 after it pops and hesitates and pulls threw it..

[hanzbrady]

Have you tried a verified working CAS?

[Drift24tsx]

If I start it now let run for 20mins never touch throttle rpms at 700 cas in middle timing shows 15 all good running well minus occasional misfire heard threw exhaust. Now I move throttle real quick maybe 1500 2k Rev idle stays high and shows 30 or 0 20 whatever just not 15 where it was. Walk away for a hr come back and it's still idling a hair high and timing not at 15.. most cars I've timedone you can snap throttle and it returns back to base timing. Never seen one jump around like this just from snapping throttle.. wish I could post a video...

[Drift24tsx]

Cas seems ok I guess only tried the 1.. if I tap on it wiggle wires wait around nothing changes it other than a quick throttle snap. I am getting a knock sensor code as well apparently I just checked code 34..

[tb13]

With those symptoms I'd suggest you check the following:

CAS
TPS
MAF

Google how to verify each is working properly then check back here. There really aren't a whole lot of sensors to go bad, so I'd put money on something I listed above being out of spec or dead causing you issues. If everything checks out, pop your ECU open and look for capacitors that are leaking or puffed or even water damage.

[Drift24tsx]

Awesome thank you! I think tps is good sits at .45 wa4m idle until Electric fans come on drops to .42-.43 but if I snap throttle goes back to .45. I will check maf and see what test I find hope cas is good I figured if it was firing injectors it's fine.. I'll look for a test on that as well. Thanks again I'll post if I find something going on!

[tb13]

Awesome thank you! I think tps is good sits at .45 wa4m idle until Electric fans come on drops to .42-.43 but if I snap throttle goes back to .45. I will check maf and see what test I find hope cas is good I figured if it was firing injectors it's fine.. I'll look for a test on that as well. Thanks again I'll post if I find something going on!

The TPS reports throttle input back to the ECU, I have seen TPS's read properly at idle, set at .44-.46, but that have a dead spot or two. This causes the ECU to go from seeing throttle input to seeing nothing.

Also, are you getting any trouble codes from the ECU?

[Drift24tsx]

I am getting a 34 knock code and 54 auto to ecu and is a s13 auto to manual car. I have a wiring specialties harness but not the knock harness. I had to dewire from factory harness and and re pin to wiring specialties harness connector. I know front and back was right pin and assumed other 2 in connector were each ground as it was in factory harness. Seems twice as long as it should be tho but wanted to just depin connector and slide pins in new with no cutting. If I clear codes start it 1min turn off check codes 34 knock code is there already.

[tb13]

Sounds like either your attempt to re-pin the connector is causing issues or you have a bad knock sensor. Considering your motor is probably 25 years old, its probably time to replace your knock sensor. Code 34 also puts the car into a limp mode, if I recall correctly it makes it run rich and pulls timing to keep the motor safe. Along with the stuff I listed above, check your knock sensor and harness for issues and try to get rid of that code 34.

[Drift24tsx]

Ok so there was a bad contact at my knock sensor and repaired so now no codes just the 54 for auto to ecu. When I first start car timing at about 30 on the last mark of pulley. When it warms up sits right at 20 with the cas dead middle of the bolt holes. Took for a drive and just feels so sluggish almost like a couple cylinders drop but don't feel a miss however there is a irregular miss at idle. When I got back put timing light back on to check and timing was glitchy looking would say 30 then show like 1 inch past 30 like 80 if there was that many notches lol.. but jumps around real quick but I can see for a split second 30 and quickly to no notches at all. If I had to guess switches like 10 times every few sec its fluctuating really fast! If I unplug tps sits at 30 no glitch ingredients or fluctuations. But how was 20 idling for a hr... throttle snaps and all went right back to 20. Drove it got it hot now bouncing everywhere. Possibly bad cas? Normally bad cas are no starts..

[greenwood]

Do a compression check.

Make sure TPS is set in idle mode, This guy has a pretty nice video. I get it's for a z32tt but I had a rb20det and pretty sure I remember the process being the same:
https://www.youtube.com/watch?v=i37NIF_SUCQ&t=236s

Also make sure your spark signal you are getting for cylinder 1 is correct.

For the Z32 you run off the PTU (ignitor) there is a lengthenged cable that you put the timing light guy around. On the rb20, I don't remember, but on my rb20 I set timing off cylinder 1, not the ptu/ignitor, it was harder this way to get a good signal.. I do remember the rb20 igntor sucks and it's best to upgrade to j30 ignitore or something. I upgrade mine.

Your problem could be a boost leak causing it to fall on it's face with improper timing.

Are you sure your injectors/fuel filter is good, correct spark plugs and proper gap? all good coils (bad could cause miss rb20 ones go bad a lot, run no coil pack cover to keep them cooler, all this little shit unfortunately adds up.

[Drift24tsx]

Yea tps is good new plugs gapped at .030 no boost leak hold right at 10 and only 4 couplers I know are sealed. Has spitfires with ws harness z32 fuel filter walbro pumpg used fp guage today read 39-40 and 46 unplugged vacuum. May be high but unsure would cause this.. drove alittle bit ago pulled hard then started to loose it on top end again.. feels like no fuel 3/4 to full throttle pulls the same stomp up and down pulls the same.

[tb13]

Yea tps is good new plugs gapped at .030 no boost leak hold right at 10 and only 4 couplers I know are sealed. Has spitfires with ws harness z32 fuel filter walbro pumpg used fp guage today read 39-40 and 46 unplugged vacuum. May be high but unsure would cause this.. drove alittle bit ago pulled hard then started to loose it on top end again.. feels like no fuel 3/4 to full throttle pulls the same stomp up and down pulls the same.

Did you open up the ECU like I suggested? If everything is perfect and it still runs like poo, you should check the ECU for bad capacitors.

[Drift24tsx]

Ok no I did not do that going to drive it to work 30 mins tomorrow see how it does on a decent drive vs 5mins.. I'll try looking inside of it tomorrow thanks !!!

[Drift24tsx]

So opened ecu looked ok even got out a magnifying glass to look for cracked soder.. drove some more always warmed up 1st then drove and would still do the full throttle feels like cuts out then start to back off and pulls hard.. so I drove today started and hopped right in and went car wouldnt even move gave gas and nothing then as you would back off would chirptires quick and go.. so I started thinking maf? Looked at it and it's a z32 last owner had a neo apexi fuel controller and I removed with my swap. I'm wondering if it's to big I ordered a rb20 one anyway to see but any thoughts? As the car warms up it gets better and can pull threw the gears just holdS back still but not nearly as bad as cold.