terroRX7

hi all

I bought a 89 Caprice (sorry) with totally stock L03 TBI
it doesn't start when cold unless I keep my foot on the pedal for a while
and it will stall immediately if I remove it ( in the first moments )
after around 30 seconds I can let the pedal but it will idle very low and a bit rough

overall performance when hot it OK and hot starting is OK

I've replaced TBI intake gasket, Spark plugs, wires, Engine Coolant Temp sensor, O2 Sensor, fuel and air filter
and checked all vacuum lines for leaks

no SES light running ( maybe disconnected by the last owner ... I don't know )

what should I look for ?
also what is a good scanner for these engines ?

thanks

NovaSS Kid

I don't mean to hijack this thread but I have the exact same problem. Whoever can fix this will be my hero!

I have an '88 350. It runs real rough for about 30 secs. when cold and then like a switch was flipped it smooths right out and idles fine. As it warms up the idle comes down normally. Hot start and idle are OK.

I have replaced CTS, O2 sensor, fuel pump and filter. Plug wires, cap and rotor are new. I have a scan tool running on it and all sensors are good and reading correctly. ( IAC, TPS, EGR, O2, CTS, MAP) I have no SES light or stored code. Fuel pressure is good. (12 PSI)
Engine is sound with good compression.

This engine is in a 64 Nova but the engine is stock.

Thanks to anyone who can help!

Tim

RFmaster

'RX7

1) SES light should turn on blink off and remain solid on when ignition key is placed into run position from off position. If SES remains unlit, you can test SES light functionality right at the ECM connector, Pin A5 Brown-white wire. Back probe connector with a DVM and observe voltage. A test light can be used as well. Also, shorting Pins A & B together (paper clip trick) of the ALDL test connector will force ECM to flash stored fault codes, if any (if only code 12 is displayed - all is well)

2) You may have a flaky or worn out TPS. When cold and before starting engine check TPS voltages (ignition key in run position). Pin B is TPS output (dark blue wire) and should be about 0.3 to 0.6 Volts at idle. Pin C is 5 Vdc reference (Gray wire), Pin A is a ground (black wire). At WOT Pin B should measure close to 4.5 Vdc. Voltage readings should be consistent with either engine cold or hot.
3) Verify your fuel pressure at cold vs. hot. TBI system does not have a FP test port. You can rent FP tester with a TBI T insert. Fuel pressure regulator springs are known to break or get weak with age resulting in flaky fuel pressure.

4) The best scanter - thats a can of worms. I use Tuner Pro or WinALDL with my laptop.

//RF

terroRX7

thanks dude

I built an ALDL cable and checked it ( but I forgot to erase old codes ) so I got
13 O2 ( when I bought it the O2 sensor was disconnected )
22 TPS ( I disconnected it one or two days before to check it )
23 IAT
32 EGR ( previous owner removed EGR equipment except for the EGR valve in the manifold so I have to order an EGR delete chip )
42 EST ( maybe because we disconnected it when we changed the distributor )


I tested the TPS with a DVM and I got 0.63v closed and 4.5+ @ WOT
and the voltage doesn't spike if i open the throttle gradually

but under Sensor Data in ALDL the IAC shows 0 always does that mean it is bad?

I will check for the SES light ASAP
and I don't have access to a fuel pressure gauge now I will try to get one

many thanks again

RFmaster

'RX7

Well, start taking care of these codes one at a time. You can clear them by disconnecting battery for about 1 to 2 minutes.

Since you have a 21 year old car the chances are that you have a very tired fuel pump. The only way to find out is to perform a FP check with a gauge. FP gauges are available for rent at better auto parts stores.

//RF