Cleancrxman

HEY GUYS,
I picked up a super clean 91 crx si. it has a dohc zc swap. motor seems very good. only issue. is that it kinda stumples until 3k. then it takes off as it should.
I think it may be ignition timing related.
but the problem is. when I got the car, someone had cut the dizzy so u could advance the ignition timing. seemed to be running really rich. so I ordered a new dizzy, and when it got here. I noticed they were the same dizzy. off an 89 integra. one was just cut to run advanced and the new one was not. so I installed the new one without any issue. but the bog seems to be worse. is there any reason that someone would need to cut the dizzy in order to run a 89 integra dizzy on a dohc zc. I am also running the 89 integra ecu.
NO CHECK ENGINE LIGHT. the only code I get is o2 sensor. and that's only sometimes. the but the car stumples even when its off..
any ideas what I should check?

4drEF

Could be the O2 going bad.
They don't always throw a code when they aren't working well.
They get "lazy" and send info a little late. Keeps the ECU happy, but engine runs poorly.

Did you set the ignition timing properly - disabled ignition advance by shorting the service connector?
Also, do the check on your TPS to make sure it's right.

swordofdoom

Check your wiring, TPS, MAP and Dizzy.
You have something either backwards or not connected properly.

stratman3

Did you figure it out? I'm having the same issue, the car only runs half decent if the timing is way advanced.

4drEF

Sounds like you might not have your timing belt on correctly.
Maybe a tooth off.

jlicrx

i would agree - if they had to cut the attaching arms on the distributor in order to get more ignition timing advance, the intake camshaft is probably not correct

same answer - not enough advance = camshaft incorrect - if the intake cam is correct, the distributor attaching bolts should be in the center of the slots

stratman3

I've checked and triple checked the timing marks, and they are dead on. I even took the valve cover off to make sure the dowel holes were lining up and they are. Here are some pics, What I'm I missing is there an alternate timing?







And the crank is at the single line away form the other three

swordofdoom

Stick a long solid thin metal into cylinder one and see if its at its highest when your at TDC.
If it is, you might want to consider checking your Fuel pressure regulator, fuel filter and even your ECU. Remember a PM6 will run the motor but will not run it at full potential/

4drEF

How is your crank lining up?

swordofdoom

I just redid my timing today It ran like crap.
I was off two tooth on the Intake side.
There is a scratch / line mark on the crank just have that tooth point straight towards the arrow on the oil pump housing. That is perfect TDC.

What I did was TDC for the crank, TDC for the Exhaust cam and using a 12 MM i turned the Intake clockwise towards TDC while allowing some slack for the tensioner to work its magic on the belt. Bam got everything at TDC and got tensioner tight at the same time.

I spent nearly 2 hours on the timing since I couldn't get it right the first time, 2nd and this is prob the 10th time I tried it. Now it runs and Idles like a champ on my chipped P06 running a B16 Map with vtec turned off.

I tested the motor with a P29 OBD1 DOHC ZC map and it ran like crap...

stratman3

Ok, timing is dead on and #1 cylinder is at TDC. Going by the mark on the cam cover the crank is lined up with the single mark on the crank pully which i believe is TDC. I also took off the crank pully and the mark on the crank gear lines up with the mark on the oil pump. Even took off the dizzy cap and the rotor was also pointing to the #1 plug.

Now the motor when i got was obd0 running a pm6 ecu. I wanted to be able to tune the ecu so i went ahead and coverted it obd1. Im now obd1 running a p75(obd1 b18b1 ecu) with a p29 basemap. Also a TD43U dizzy. The fuel filter is new and the FPR is aftermarket. Should i try running a different basemap or ecu ?

swordofdoom

Yeah that P29 base runs like crap. I tested it yesterday and it would actually die out on me after a hard rev in neutral. Plus it seems to hesitate if you stomp on the gas especially at the 2.5-3K range. I ran a dyno map for a vtec motor and this map actually redline pretty smooth and shocking fast. Although, it prob needs more tuning since its blowing out a lot of carbon without a cat on the car.

stratman3

Running great now with a new base map, thanks everyone for the inputs.