Engine not responding to full throttle... 87 TII.
 

I picked up a parts car to do a 1st gen turbo swap, but before I yank everything out I figured I'd try to get this thing running right first. The car sat for almost 2 years according to the previous owner. I drained the gas, changed the starter, replaced the battery, etc, etc. Amazingly enough she started right up.

She's idling nicely at 1k rpms and will go pretty high into the rpms if I give it just a partial or slight throttle, as soon as I try to go more then 1/3rd pedal she hesitates and surges...? Any advice....?? Honestly I don't even know where to start.

The car is a 1987 turboII. I do know half way threw the year Mazda changed and this one has the ceramic resistor on the passenger fender wall. The car seems to be fully intact and unmolested under the hood except for a 3" straight threw exhaust. Thanks for any help.

Test the throttle positioning sensor.

In what RPM range is it hesitating/surging?

did you change any fuel filters at all?
In tank or on body?
2 year old gas is not friendly.

^ Also a good point.

And I would bet the fuel injectors may not be operating to full potential.

are you driving the car when this occurs or just free reving it?
if your driving it, and its doing this do you have a boost gauge?
with a fulle xhuast on the car its probable that your reaching the fuel cut point, from over boosting. and that's why its bogging out.
is it a stock ecu?

sounds like a fualty TPS or secondary injector issue.

:nod:

The car seems to be totally stock except for the exhaust, which again is a 3" straight thru from the turbo all the way back. No cats and two magna flow mufflers at each end. It does have a oxygen sensor right off the turbo which appears to be hooked up.

I changed the fuel filter up front w a new one and pulled the pump today. The filter in tank before the pump looks clean, just to be safe I sprayed it w carb cleaner and some compressed air. Inside the tank looks really clean and even when I drained the old gas it came out still smelling and looking decent.

I picked up this stuff today... I don't want to dump it in just yet with out you guys opinion.

Attachment 679033

So after changing out fuel filter, and cleaning / checking out pump, she still does the same thing. It def feels like the secondaries aren't kicking in...??

I'm thinking the previous owner upgraded just the exhaust not knowing any better, had nothing but problems since, which is why the car prob sat there for two years. He did include a brand new Hitachi 20B/Supra fuel pump that was never installed.

Again, the car does look all stock except for the exhaust.

I'm ready to start tearing into whatever I have to, I really want to get familiar with her.

So far she's only been started and ran up in the air on two sets of jack stands. Boost gauge goes up to the 0 point but hasn't went past.

Anytime I go past 1/3rd pedal... Or if I stay light on the pedal she'll get up to about 6k before it happens.

Unless you trick the car into thinking it is under load, the secondary injectors will not turn on under these conditions.

Alright... I'll take her for a spin around the block tomorrow. Although when it hesitates and or surges its not a slight one... This thing is completly falling on its face.

check the part numbers for the pressure sensor and on the ECU, should both be N318

If the TPS plug is disconnected and the vacuum hose to the Boost Sensor is unplugged this will trick the engine into thinking it is under load so you could attempt to activate the secondary injectors while reving the engine above 3800 rpm in neutral. Otherwise, the secondaries will not turn on, thus your hesitation problem's root cause cannot be the secondary injectors.

Attachment 678944

Defiantly not 318, w/a HKS Fuel Cut.

well the ECU is from an '88 not an '87, some more specifics would be required unless the car is actually an '88. i was wrong about it needing a 318, '87 turbo ECU is a N332.

does it have a resistor pack mounted to bottom of the RF fender skirt inside the engine bay behind the RF headlight? it shouldn't, if it does then the ECU is wrong for the application or the resistor pack needs to be removed and bypassed. the N333 will work but it depends on the resistance of the injectors, '88 had high impedence injectors and no resistor pack, '87 had low impedence injectors with the resistor pack.

it will work but the combination above needs to be correct and could be the issue.

So I've been searching for two days for the title to the car to verify if it's really a 87 and I can't find it yet among the overwhelming piles of shit I have at home, lol. Is there anyway to tell the year off the car...? Vin, door jam sticker, etc...??

My buddy has a 88 that's down that I can use whatever I want off of for now. It also has a 333 ecu.

7/87 and above generally is going to be an '88 model. the build date is on the tag in the door jamb.

I am having the same issue, I just took out a racing tuned N332(don't know who tuned it) and put in a stock N332 to see if it made a difference and I tested my TPS and it is still stumbling while free revving but have not drove it yet.

10th digit of the vin will indicate year. I don't know the year codes for the 80's, but you can cross reverence it online.

Drivers door jamb says 08/86... Tenth digit of the vin is an H...??

JM1FC332XH0508388

H = 1987

http://www.mmtcta.org/excisemanual/VINYOMtable.pdf

Thanks for all the help...!

I'm going to pick up a ECU tomorrow from another 87. 1987 the low impedence w resistor pack stopped half way threw the year, right...??

Yes, sometime late in the production run. Regardless, the ECU looks for high impedance one way or the other.

i would check to see if the car has the harness and/or resistor pack, if there isn't one then your ECU is correct for the car assuming the injectors are high impedence as well.