Some background on the vehicle.

1987 RX7 TurboII
Series 4 Japanese motor

We did not do the swap, it was done by a previous owner. We bought the car in running condition, but it wouldn't boost, wouldn't rev past 4k, wouldn't idle, etc. Now, it sorta idles (on 1 rotor usually until 2k rpm), boosts to 6-6.5 PSI and runs to 5.5-6.5k before doing a huge and violent backfire then will run to 7k.

The wiring harness was half gone when we got it so it's been rewired from some other T2 harnesses and everything is now connected although we need to test some sensors, replace lower intake manifold gasket (doesn't seem to be leaking but..). Timing was set to 5 degrees (L1) when the guy rewired the harness.

It takes a bit to start, sounds like a bad battery but it's not.. when we last checked compression it was ~9.4kg/cm2 for all three sides of the front rotor and ~9.2kg/cm2 for all three sides on the rear rotor.

There's some obvious (IMO) fuel and ignition issues (oh, swapped coils/wires with spares I had laying around and put in new plugs) but any ideas/help would be greatly appreciated.

FWIW: I don't know if it's using the US ECU, which crank angle sensor, etc. I know the intake manifolds are mixed (lower is the japanese one and upper is the USDM one).

I'd REALLY love to compare it to a local T2 but haven't found any yet.. IMO that comparison would be so nice to find misrouted vacuum lines, etc.. but I guess I'll just follow the vac diagrams instead..

Here's the graph, thanks for any help/suggestions/ideas.

 

anyone?

 

that is way WAY to lean!!!!

 

have you tuned it at all? that a/f is all over the place. sounds like the previous owner did a shitty job and couldn't fix it, so he sold it.

 

Stock fuel pressure, stock ECU, stock injectors, etc. not much to tune with. the A/F is far far too lean I agree, which is one thing I'm trying to figure out. Completely stock at LESS then stock boost levels, why is it so lean?

 

What sort of O2 sensor or A/F reading was used? The best is a whide band screwed right into the manifold.

Wat boost pressure are you running?? Something is wierd.. You say you have less than stock boost pressure but 200 or so at the rear wheels. Was the dyno rigged?? What sort of bolt ons do you have?

Get a walbro in tank pump from www.autoperformanceengineering.com

 

The large dip at 4300 rpms is where your secondary injectors start firing. This is also known as the "3800" rpm hesitation. The dyno seems inaccurate. Reground the ECU and some sensors. Alsmost seems like your secondary injectors arnt firing properly. Try regounds everywhere.

 

You wrote that you're getting around 6-6.5 psi on a stock 87 TII but also say your getting less boost than stock. Max boost on a stock 87 T2 is 5.5 psi with fuel cut around 7.5 psi.

 

Wideband hooked up to the dynojet in the end of the stock downpipe.

6-7PSI (regarding that, I *THOUGHT* 7.5psi was stock, but I guess 5.5PSI is, so it's running a little over stock boost I guess). We dynoed 15-20 cars the same day, all read normal numbers so I have to assume this pull is just as accurate as the other pulls :shrug: Stock intake box, stock filter, stock downpipe, nothing after the downpipe, etc.

Cameljoe: Again, sorry about the "under stock boost" I thought the stock boost level was 7.5 not 5.5psi, my bad.

 

You wrote that the wiring harness has been rewired because it was missing connections. I would check those connections and then sensors that they connect to. I have to check the FSM to see if it gives you the different voltage readings that ECU/sensors are seeing.

 

my stock t2 (88 model) with a mild exhaust boosts 6.5psi and makes approx 145 hp at the wheels... I find it very hard to believe you're making an extra 50hp with the same boost. Is the dyno readout attempting to correct the rwhp to flywheel? that would make sense I guess...

as for the air fuel ratio, mine makes a steady progression down from about 14.8 to 13, as the revs rise. This was apparently perfect (for my stock vehicle) but I'm fairly unsure on that...

Charlie

 

was that timing 5 or -5??

 

Im no dyno expert by any means at all, but you see the dip at around 5500 RPMs you have a sudden dramatic drop in HP/TQ, and then at about 5800 you have a sudden leaning of the mixture, can this be realated? The only thing i can think of, and its a long shot, is that there was some lag on the wide band, say it was stuffed in the muffler or something, and was having a delay, and sensed the mixture being lean at a later RPMs. What im wondering is if you ran into any detonation during the run and droped the HP/TQ. I dont understand why their would be a drop off like that for no aparent reason. Someone help me understand maybe?

 

Well I have a TII but am in the process of putting everything back together myself. Missed the dyno day because if it Hey how much would you guys charge me for some dyno tuning with my s-afc?

 

Going to be doing that when I have the time.. hopefully this weekend. If I can get a lower intake manifold gasket by then I'll do that at the same time.

What would be the symptoms of a bad pressure sensor?

 

Nope, that is wheel horsepower. For all I know it might be street ported. The motor was in the car when we bought it and it's a japanese spec motor, but I've never torn it apart to see what has been done to it.

Oh, my compression #'s above were wrong, that was for one of our 12a spare race motors, the T2 has 8.6kg/cm2 front and 8.4kg/cm2 rear compression.. about equal on all three sides (8.6, 8.5, 8.5; etc) measured by a comp-07 digital rotary compression tester.

NRA T2: 5 degrees "BTDC" if you can say that in the case of a rotary..

Roy: You're guess is as good as mine. This is our first T2. No detonation was HEARD but open downpipe is loud as hell. Evil Avaitor, JerryLH3 and one other rx7club.com guy where there for the pull and didn't mention any detonation so I'm assuming they didn't hear any either.

Ryde: I'd love to compare our cars when your's is done. It'd make some stuff a lot easier I think.

edit: Thanks for the info/comments/etc so far everyone. We are going to check ECU codes (well the first one :P ) tomm and see if it's throwing a code. And hopefully will be able to invest the time this weekend to check all the sensors. Also want to spray carb cleaner everywhere and see if I can find a leak.. didn't before but it's worth a try again.

 

btdc? you probably want atdc (5)

 

Here's a all stock S5 TII dyno. It's a helluva lot smoother...

 

I'll check it again. It's got those marks on the crank as well to set it with. I'm hoping to take off the UIM/LIM, etc this weekend so will set timing again after verifying the sensors are good.

 

I'm pretty sure the dyno was reading accurate numbers. None of the ITRs thought anything was wrong and they all pulled about the same numbers with the same mods. My S5 N/A pulled a 139.7 RWHP on it's best run, and an S4 N/A pulled 130 RWHP on it's best run. That S4 last time dynoed at 120, and now has a stand alone. These numbers (at least power) make a good amount of sense to me (well, I hope, otherwise I got all excited about 139.7 hp for nothing ).

Hope that might clear that up.

 

Yep, I have to agree. A red MR2 based on it's previous dynos said he should get abour 330whp, he got 331, craigs ITR read EXACTLY what we figured it would based on it's dynos before, others got exactly the same number s(+/- a few of course) as they got on other dynos. The dyno is as a dynojet will get.

 

So Dave how much will they charge me when I need to tune my car?

 

I think normal rates are $120/hour with wideband a/f

the shop's number is 727-571-1450, ask for John.

 

******* ****.... how long does it usually take? thats INSANE prices!!!

 

insane cheap? or expensive? most of the shops around here are 100-150/hour with wideband.