2.3L ('83-'97) 1996 B2300-Beating my wallet to death.

[kblast523]

Purchased 1996 Mazda B2300 SE in October, cheap. It had 155,209 miles showing on odometer since Feb 2009 according to Carfax. Tires are 50% dated 48th week of 2017 (Hankooks).
Began by replacing all hoses (all factory) thermostat, water pump, serp belt, all pulleys, ps pump and lines, plugs, ,plug wires, TPS, MAS, timing belt, timing belt idler, spark plugs and wires, Cat converter, up and downstream O2 sensors, valve cover gasket, oil and filter, fuel filter and hung air freshener on the mirror. Flushed mud out of block, radiator and heater core. Even replaced battery and fixed ground connection that was gnarly.
It started and ran, barely. It would run just fine above 2000 rpm. Had (as I recall) about same amount of power on highway as my 1988 with the same engine did. Won't idle.
Replaced fuel pump on diagnosis of low fuel pressure from a certified ASE mechanic. No change. Put a different MAS on it from a know running vehicle. No change. Replaced fuel injectors. Slight change in hp, still not idling correctly. It'll rev to the moon, but below 15-1800 rpm gutless. Timing checked by four different mechanics and all report the marks are lined up.
Anybody have any suggestions?

 

[racsan]

fuel filter? I know it should be standard procedure to replace when putting a new pump in but sometimes it can be forgotten. Only other things I can think of is a possible vacuum leak or the I.A.C. valve.

 

[kblast523]

I've put two fuel filters on and an IAC valve. It behaves the same unplugged or plugged in...could that be the culprit? Seems to be running only slightly rich. Two different wrenches checked for vac leaks...could that be a bad brake booster,? it seems a little weak...

 

[Shran]

I would suggest doing a compression test on it to make sure that you don't have a valve hanging up or weak cylinder(s)

 

[Blmpkn]

Daaaaamn when you fire the parts cannon that enthusiastically... no wonder it's draining your wallet lol.

 

[kblast523]

Replaced injectors. Runs none better, but more power. Did compression check, 1-155, 2-156, 3-159, 4-156. Oh, and the guy who did the compression check called to tell me he had only one compression gauge and needed two because of the dual plugs....yeah, right. On the brighter side, he also informed me my 500 mile old Autolite Double Plats needed to be replaced because they were 'burned open' to .44 inch gap..."It'll run better with new plugs." Kids now days...

 

[dccarpenter]

Coil packs maybe? I didn't have the idle issue but gutless under 2k rpm. I changed the plugs to regular Autolite coppers and changed the coil packs and it made a world of difference. I had previously done iac, air filter, belt, timing belt, fuel filter, checked timing, and other misc. items to no avail

 

[89Twincharge]

Check crank sensor some times contamination(oil/dirt) can cause mis reading, hit it with brake clean. I would replace the timing belt regardless stretchy belts may look "fine" when engine off, that can cause low "power" till about 2k. If you remove iac and leave plugged in have some one turn key forward see if valve moves, also clean iac and throttle body holes where iac mounts.

 

[kblast523]

First, has a new timing belt. I have cleaned all the ports on intake, replaced IAC previously. The injectors DID (do) help, with power on highway, still not and never will be a road racer. For those of you wondering, in over 1k miles it has not used oil. NAPA High mileage 5w30 stopped all the leaks that appeared to be from rear main and oil pan. I will try brake kleen on crank sensor, it was wiped clean during previous maintenance. Still has idle issue, below 1,100 rpm stumbles and stutters. Previous post mentioned coils, guess I could grab hold of them and see if I get zapped! (JK) If I find a fix, I'll advise. It DOES run better than it did...

 

[89Twincharge]

Seafoam the oil about 100 miles before next oil change hla's maybe sticking.

 

[pwrshft99]

Stretched throttle cable?

 

[scotts90ranger]

The throttle cables don't affect the 2.3L's much, they have an eccentric linkage deal that tries to make the throttle fairly linear, but then again I only have experience with a couple... I spend time at WOT but not much, and the issues I've had with throttle cables have been a burr just off idle that holds the throttle open or makes it hard to open at idle...

I'll admit that I think the '97 I have is more gutless in the low end in first gear than my '90 was when stock... I like speed density better than MAF...

That said, I never recommend throwing that many parts at things, especially in this day and age, old parts are likely better than some of the current offerings... It sounds like most things have been ruled out but you never know what jackhole owned it before did to try to "fix" things... If memory serves there are some criteria that needs to be met to go into idle mode, namely a certain engine speed and throttle position, If someone monkeyed with the throttle stop screw that can screw things up... or if the TPS isn't working right.

 

[kblast523]

Thank you everyone for your input. Throttle cable is fine. One of the last things replaced was TPS, and had to grind screw heads off and retap throttle body, the steel FACTORY screws were seized in the aluminum. With the coil(s) installed we finally have near decent idle. The left bank coil pack (wouldn't you know) was not sparking unless over 2-2,500 rpm. and of course replacing the right coil pack not easier. Also put a replacement IAC on and it had no effect at first, but after two or three trips, suddenly idle increased to 1,000 rpm. And with that, found the AC compressor running! Turned off the AC and idle, for the first time at 800 rpm.
And as info, this truck is a two owner, mostly in the Texas Hill country and west Texas, and with 155,208 miles showing on odo since Feb 2008 (13 years no odo) and moving from Fredericksburg to Coleman to Amarillo. And all the front suspension parts have been replaced, joints have grease zerks. The single part that wasn't a factory installed piece other than maybe the timing belt and plugs, is the IAC.